Obstruction retrieval devices

ABSTRACT

Retrieval assemblies configured to capture an obstruction located in a bodily duct of a patient and associated methods of manufacture are provided. According to one implementation a retrieval assembly is provided that includes a distal collar fixed stationary on an elongate wire, a proximal collar slideable along a portion of the length of the elongate wire, and a plurality of shape memory elongate clot capturing elements that each has a proximal end coupled to the proximal collar and a distal end coupled to the distal collar. The retrieval device is configured to automatically transition from a radially constrained state to an expanded rest state with the proximal collar located nearer the distal collar when in the expanded rest state. As the retrieval device transitions from the radially constrained state to the expanded rest state, proximal portions of the clot capturing elements invert around the proximal collar.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/379,080 filed Apr. 9, 2019.

FIELD

The present invention relates to devices, assemblies and methods forremoving obstructions from a bodily duct of a patient, such as, forexample, removing clots located within the vasculature of a patient.

BACKGROUND

Existing clot retrieval devices are based on the concept of passing aguidewire through or near the center of the thrombus until the guidewireis beyond the thrombus, passing a delivery catheter over the guidewireacross the thrombus and then exchanging the guidewire for a retriever.The delivery catheter is thereby withdrawn, exposing the retriever tothe clot to enable capture after expansion of the retriever. This isfollowed by withdrawal of the clot-containing retriever device into anaspiration catheter positioned proximal to the clot of sufficientdiameter to enable retrieval of the device with retention of the clot.One such retrieval device is the Solitaire™ revascularization device.

Most clot capturing elements of current retrievers are made of Nitinoland passively expand into and through the clot using the intrinsicradial force of the device prior to retraction of the device to removethe thrombus. This radial force is through thermally-induced,martensitic transformation of the Nitinol elements of the device by apredetermined shape change in the geometry of the Nitinol. By necessity,this expansion produces shearing and fracturing of the thrombus, sincethe clot capturing elements cannot expand through the clot to contactthe vessel wall without producing linear defects within the clot. Thisclot shearing and fracturing can in turn increase the risk of distalembolization.

An estimated 700,000 patients in the U.S. and 950,000 in Europe sufferischemic strokes each year, the majority of which are large vesselocclusions (LVOs). Some of the pivotal randomized prospective clinicaltrials to date have established the superiority of radially expandableretriever devices over drug therapy alone for LVOs of the anteriorcerebral circulation. These clinical trials include: MR CLEAN, withpublished analysis appearing in the New England Journal of Medicine2015; SWIFT PRIME, with published analysis appearing in the New EnglandJournal of Medicine 2015; ESCAPE, with published analysis appearing inthe New England Journal of Medicine 2015; EXTEND IA, with publishedanalysis appearing in the New England Journal of Medicine 2015;REVASCAT, with published analysis appearing in the New England Journalof Medicine 2015 and THRACE, with published analysis appearing in LancetNeurology 2016.

The published analyses of these trials have not emphasized the number ofnew ischemic strokes in the interventional arms of these studiescompared to standard medical therapy. These new strokes are attributedto distal embolization, vessel spasm or dissection. In the MR CLEANstudy, 5.6% (13 of 233) of patients in the retriever arm had clinicalsigns of a new ischemic stroke in a different vascular territorycompared to 0.4% (1 of 267) in the control group, representing a 14-foldrelative risk. In the REVASCAT study, 4.9% of patients had distalembolization into a new vascular territory compared to none in thecontrol group, and 12.7% had local arterial complications attributed topassage of the retriever device (3.9% dissection, 4.9% perforation, and3.9% vasospasm requiring treatment) compared to none in the controlgroup. In the THRACE study, 6% had distal embolization in a newterritory, and 26% experienced vasospasm, dissection or perforation.None of these events occurred in the control group.

The number of additional passes (withdrawal of the retriever across theinitial clot-containing segment of the vessel) has also beenunderemphasized in the clinical trials of these devices to date. Eachpass of a retriever requires manipulation and advancement of a catheterand guidewire across the segment of the thrombus-containing artery toenable repeat delivery/deployment of the retriever, thereby creatingpotential vessel injury in the form of vasospasm, dissection orperforation. In a recent study, as many as 5 separate retriever passeswere required for intended thrombus removal (REVIVE 2018) with a mean of2.2 passes. The Instructions for Use (IFU) for the Solitaire™thrombectomy device (sold by Medtronic) instructs physicians to performno more than three recovery attempts in the same vessel. The IFU for theTrevo™ thrombectomy device (sold by Stryker) instructs physicians toexercise caution when withdrawing the device through an area or arterialvasospasm. The 3D Revascularization device (sold by Penumbra) enables upto 5 passes of the retriever device, each of which requires re-crossingof the target vessel (e.g. M1 segment of the middle cerebral artery)with a catheter and guidewire.

SUMMARY

Obstruction retrieval devices, assemblies and methods are disclosedherein along with methods of manufacturing retrieval devices. Althoughthe example implementations disclosed herein are directed to the removalof blood clots located within an artery of a patient, it is appreciatedthat the devices, assemblies and methods are applicable to the retrievalof other types of obstructions located in other bodily ducts of thepatient.

According to some implementations a clot retrieval assembly is providedthat includes an elongate wire and a retrieval device mounted on theelongate wire. According to some implementations the retrieval deviceincludes a distal collar fixed stationary on the elongate wire and aproximal collar that is slideable along a portion of the length of theelongate wire. Extending between the proximal and distal collars are aplurality of shape memory elongate clot capturing elements that each hasa proximal end coupled to the proximal collar and a distal end coupledto the distal collar. According to some implementations the retrievaldevice is configured to assume a radially constrained state, an expandedrest state and an expanded stressed state. When the retrieval device isin the radially constrained state the proximal collar is located at afirst axial position on the elongate wire proximal to the distal collarand is spaced apart from the distal collar by a first distance. When theretrieval device is in the expanded rest state the proximal collar islocated at a second axial position on the elongate wire proximal to thedistal collar and is spaced apart from the distal collar by a seconddistance that is less than the first distance. When the retrieval deviceis in the expanded stressed state the proximal collar is located at athird axial position on the elongate wire proximal to the distal collarand is spaced apart from the distal collar by a third distance that isless than the second distance.

When the retrieval device is in the radially constrained state and theconstraining force is removed, the shape memory characteristic of theelongate clot capturing elements causes the retrieval device totransition from the radially constrained state to the expanded reststate. The retrieval device is configured such that during itstransition from the radially constrained state to the expanded reststate an inversion of the elongate clot capturing elements occurs in aproximal section of the retrieval device that results in the elongateclot capturing elements assuming arched configurations. During theinversion the proximal collar transitions to the second axial positionon the elongate wire and after the inversion is at least partiallysurrounded by the arched clot capturing elements.

Upon a distal force being applied to the proximal side of the retrievaldevice, or applied to a proximal end of the proximal collar, theretrieval device transitions from the expanded rest state to theexpanded stressed state. The shortening of the distance between theproximal and distal collars urges the arched clot capturing elements toexpand radially outward and/or causes the stiffness of the elongate clotcapturing elements that form the arches to increase as result of a morepronounced bending of the shape memory elongate clot capturing elements.In either event, the retrieval device's clot capturing capability isenhanced by an increase in radial force being applied by the arched clotcapturing elements and/or by an increased rigidity of the arched clotcapturing elements.

According to some implementations the shape memory elongate clotcapturing elements are independent elements that are fixed at theirproximal ends to the proximal collar and at their distal ends to thedistal collar. According to other implementations the proximal collar,distal collar and shape memory elongate clot capturing elements areintegrally formed (i.e. made from a single piece of material).

According to some implementations the retrieval device is delivered tothe site of the clot in its radially constrained state inside a deliverycatheter. According to some implementations the retrieval device isdeployed inside the vasculature of the patient at a location distal tothe clot. During deployment the proximal end portions of the clotcapturing elements invert around the proximal collar as explained above.After deployment of the retrieval device inside the artery of thepatient, the elongate wire is withdrawn proximally by the clinician tocause the proximal end portion of the retrieval device to engage theclot. This results in a distal force being applied to the proximal sideof the retrieval device and causes the proximal collar to be moveddistally closer to the distal collar. As a result of the proximalcollar's ability to slide distally on the elongate wire after theretrieval device has been deployed, the radial force exerted by thearched clot capturing elements can vary during the retrieval process.This variable radial force characteristic enhances the clot capturingcapability of the retrieval device as explained above.

These and other implementations along with their advantages and featureswill become evident in view of the drawings and the detaileddescription.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates an obstruction retrieval assembly according to oneimplementation with the retrieval device in an expanded state.

FIG. 1B illustrates an enlarged view of the retrieval device shown inFIG. 1A with the distal cover removed and the proximal collar located afirst distance from the distal collar.

FIG. 1C illustrates an enlarged view of the retrieval device shown inFIG. 1A with the distal cover removed and the proximal collar located asecond distance from the distal collar that is less than the firstdistance.

FIG. 1D illustrates an obstruction retrieval assembly like that of FIG.1A having multiple retrieval devices.

FIG. 2A shows a side view of the obstruction retrieval assembly of FIG.1A with the retrieval device in a radially constrained state, positionedat a distal end of the delivery catheter.

FIG. 2B is a cross-sectional side view of the distal end portion of thedelivery catheter of FIG. 2A showing the retrieval device in a radiallyconstrained state inside the delivery catheter.

FIG. 3 shows a side view of the obstruction retrieval assembly of FIG.2A with the delivery catheter withdrawn proximally to deploy theretrieval device.

FIGS. 4A and 4B respectively show a proximal end view and across-sectional side view of a distal collar of a retrieval deviceaccording to one implementation.

FIGS. 5A, 5B and 5C respectively show a proximal end view, distal endview and cross-sectional side view of a proximal collar of a retrievaldevice according to one implementation.

FIG. 5D is a cross-sectional side view of a proximal collar of aretrieval device having an atraumatic proximal end.

FIG. 6 illustrates a plurality of independent clot capturing elementshaving proximal and distal ends that are respectively configured toreside in the radially dispersed openings of the proximal and distalcollars shown in FIGS. 5B and 4A.

FIG. 7A show the components of FIGS. 4B, 5D and 6 in a first assembledstate.

FIG. 7B shows the retrieval device of FIG. 7A upon there being an axialforce applied to one or both of the proximal and distal collars to causethe proximal end portion of the retrieval device to invert.

FIG. 7C shows a proximal end view of the retrieval device of FIG. 7Bwhen one or both of the proximal and distal collars is rotated withrespect to the other.

FIG. 8A illustrates a tubular member from which a retrieval device isunitarily made according to one implementation.

FIG. 8B shows the tubular member of FIG. 8A cut along its axial lengthand laid flat on a surface.

FIG. 8C shows the retrieval device having an inverted proximal endportion that is formed upon there being an axial force applied to one orboth of the proximal and distal collars.

FIG. 8D shows an end view of the retrieval device of FIG. 8C after oneor both of the proximal and distal collars is rotated with respect toone another to cause each of the elongate capture elements to assume anarched configuration.

FIG. 8E shows the tubular member like that of FIG. 8B with the proximaland distal end sections of the clot capturing elements having differentwidths.

FIG. 9A illustrates a Nitinol tube having a thinned wall section along aportion of its length.

FIG. 9B illustrates a flattened view of the tube of FIG. 9A after theformation of slots therein.

FIG. 9C shows a cross-sectional view of a clot capturing element with acurved recess formed therein.

FIG. 10A illustrates a tubular member from which a retrieval device isunitarily made according to another implementation.

FIG. 10B shows the tubular member of FIG. 10A cut along its axial lengthand laid flat on a surface.

FIG. 10C shows the tubular member of FIG. 10A upon there being an axialforce applied to one or both of the proximal and distal collars to causethe proximal end portion of the tubular member to invert.

FIG. 10D shows an isometric view of a retrieval device formed from thetubular member of FIG. 10A.

FIG. 10E is a proximal end view of the retrieval device of FIG. 10D.

FIG. 11 illustrates an insert for placement inside the annular openingsof the proximal and distal collars

FIG. 12 shows a tubular member that is cut and laid flat on a surfacefrom which a retrieval device may be made.

FIG. 13A illustrates a tubular member from which a retrieval device isunitarily made according to another implementation.

FIG. 13B shows the tubular member of FIG. 13A cut along its axial lengthand laid flat on a surface.

FIG. 14A illustrates a tubular member from which a retrieval device isunitarily made according to one implementation.

FIG. 14B shows the tubular member of FIG. 14A cut along its axial lengthand laid flat on a surface.

FIG. 15A illustrates a tubular member from which a retrieval device isunitarily made according to one implementation.

FIG. 15B shows the tubular member of FIG. 15A cut along its axial lengthand laid flat on a surface.

FIG. 15C shows the tubular member like that of FIG. 15B with theproximal and distal end sections of the clot capturing elements havingdifferent widths.

FIG. 16A illustrates a tubular member from which a retrieval device isunitarily made according to one implementation.

FIG. 16B shows the tubular member of FIG. 16A cut along its axial lengthand laid flat on a surface.

FIG. 17A illustrates a tubular member from which a retrieval device isunitarily made according to one implementation.

FIG. 17B shows the tubular member of FIG. 17A cut along its axial lengthand laid flat on a surface.

FIG. 18A illustrates a tubular member from which a retrieval device isunitarily made according to one implementation.

FIG. 18B shows the tubular member of FIG. 18A cut along its axial lengthand laid flat on a surface.

FIGS. 19A-D show a method for capturing an obstruction in a bodily ductof a patient according to one implementation.

FIG. 20A illustrates an obstruction retrieval assembly having proximaland distal retrieval devices.

FIG. 20B illustrates an enlarged view of the proximal and distalretrieval devices shown in FIG. 20A.

FIG. 20C is a cross-sectional side view of a distal end portion of thedelivery catheter showing the proximal and distal retrieval devices in aradially constrained state inside the delivery catheter.

FIG. 21 illustrates an obstruction retrieval assembly according toanother implementation wherein the proximal retrieval device is axiallymovable along a length of the elongate member.

FIG. 22 is a side view of the obstruction retrieval assembly of FIG. 22with the proximal and distal retrieval devices located inside thedelivery catheter.

FIG. 23 is a cross-sectional side view of a distal end portion of thedelivery catheter of FIG. 22 showing the proximal and distal retrievaldevices in a radially constrained state inside the delivery catheter.

FIG. 24 shows the distal retrieval device after being deployed from thedelivery catheter.

FIG. 25A shows the proximal and distal retrieval devices after beingdeployed from the delivery catheter with the proximal retrieval devicespaced a first distance apart from the distal retrieval device.

FIG. 25B shows the proximal and distal retrieval devices after beingdeployed from the delivery catheter with the proximal retrieval devicespaced a second distance apart from the distal retrieval device, thesecond distance being less than the first distance.

DETAILED DESCRIPTION

FIG. 1A illustrates an assembly useful in removing obstructions locatedwithin a bodily duct of a patient, such as, for example, the removal ofblood clots located in the cerebral anatomy. According to someimplementations the assembly includes a retrieval device 20 that isaffixed to an elongate wire 10. In use, the retrieval device 20 isdelivered to the site of an obstruction while being radially constrainedinside a delivery catheter 30 as shown in FIG. 2B. Methods of deliveringthe retrieval device to the obstruction site and thereafter retrievingthe obstruction are disclosed in more detail below.

As discussed above, although the example implementations disclosedherein are directed to the removal of blood clots located within thevasculature of a patient, it is appreciated that the devices, assembliesand methods are applicable to the retrieval of other types ofobstructions located in other bodily cavities of the patient.

According to some implementations the retrieval device 20 includes adistal collar 21 fixed stationary to the elongate wire 10, and aproximal collar 22 that is slideable on the elongate wire 10. Extendingbetween the proximal and distal collars are multiple shape memoryelongate clot capturing elements 23 that are configured to engage theobstruction when the retrieval device 20 is in an expanded/deployedstate as shown in FIGS. 1A-C. When the retrieval device is anexpanded/deployed state, the shape memory elongate clot capturingelements 23 may assume a curved configuration like those shown in thefigures or different than those shown in the figures. Hereinafter, whena shape memory elongate clot capturing element 23 is in itsexpanded/deployed state, it is referred to as “arch” or as having an“arched configuration” or “arched structure”. As used herein, the terms“arch” and “arched” are not meant to denote any particular curvature ofthe clot capturing elements 23. Notwithstanding the foregoing, the clotcapturing elements 23 assume curved configurations when the retrievaldevice 20 is in a deployed/expanded state sufficient to cause the clotcapturing elements to engage the obstruction in a manner to facilitatean at least partial removal of the obstruction during the obstructionremoval process.

In some implementations each of the shape memory elongate clot capturingelements 23 has a proximal end that is secured to the proximal collar 22and a distal end that is secured to the distal collar 21. As shown inthe figures, the proximal ends of the shape memory elongate clotcapturing elements 23 may be attached to the distal end 22 b of theproximal collar 22 and the distal ends of the shape memory elongate clotcapturing elements 23 may be attached to the proximal end 21 a of thedistal collar 21. As will be discussed in more detail below, the shapememory elongate clot capturing elements 23 may comprise independentelements that are fixed to the proximal and distal collars by a bondingagent (e.g. an adhesive, solder, etc.) and/or by a bonding process (e.g.welding). The distal collar 21, proximal collar 22 and shape memoryelongate clot capturing elements 23 may also be formed from a singlepiece of material, as will also be discussed in more detail below.

According to some implementations, when the retrieval device 20 isdeployed from the delivery catheter 30 to assume an expanded state, itincludes a proximal inverted portion 24 and a distal non-invertedportion 25. The proximal inverted portion 24 may be characterized by adispersion of the shape memory elongate clot capturing elements 23around an outer perimeter surface 22 k of the proximal collar 22 whenthe retrieval device is in a deployed state. The proximal invertedportion 24 may be characterized by at least some portions 23 c of theshape memory elongate clot capturing elements 23 being located proximalto their proximal terminal ends 23 a when the retrieval device is in adeployed state, the proximal terminal ends 23 a being coupled to orlocated inside the distal end portion 22 b of the proximal collar 22.The proximal inverted portion 24 may be characterized by the proximalend 22 a of the proximal collar 22 being located distal to aproximal-most end 20 a of the retrieval device 20 when the retrievaldevice is in a deployed state. The proximal inverted portion 24 may becharacterized by a zigzag configuration of the shape memory elongateclot capturing elements 23 in the inverted portion. That is, a portionof a shape memory elongate clot capturing element 23 initially extendsfrom the distal end 22 b of the proximal collar 22 towards a distaldirection D and then changes course to extend towards a proximaldirection P and then changes course to yet again extend towards thedistal direction D as most clearly shown in FIG. 1B. The proximalinverted portion 24 may comprise one or any combination of theaforestated characteristics.

As shown in FIG. 1A, according to some implementations the distalnon-inverted portion 25 of the retrieval device is provided with a cover27 made of a permeable biocompatible material that is capable ofcapturing fragments of the obstruction that may become dislodged duringthe retrieval process. According to some implementations thebiocompatible material is encapsulated polytetrafluoroethylene (ePTFE)with a thickness of 0.0008 to 0.016 inches. According to someimplementations the portions of the shape memory elongate clot capturingelements 23 in the non-inverted portion 25 of the retrieval device 20 donot zigzag, but extend from the proximal end 21 a of the distal collar21 continuously towards the proximal direction P.

According to some implementations, when the retrieval device 20 is inits expanded rest state the shape memory elongate clot capturingelements 23, as viewed from a proximal end of the retrieval device, forma plurality of arch structures like those shown in FIGS. 7C, 8D and 10Ewith adjoining arch structures preferably, but not necessarily,overlapping with one another.

FIG. 2A shows a side view of the obstruction retrieval assembly with theretrieval device 20 being located inside a distal end portion of thedelivery catheter 30. FIG. 2B is a side cross-sectional view of thedistal end portion of the delivery catheter 30 of FIG. 2A showing theretrieval device 20 radially constrained inside the delivery catheter.In the radially constrained state of the retrieval device 20 theproximal collar 22 is located at a first axial position on the elongatewire with the distal end 22 b of the proximal collar 22 being spacedapart from the proximal end 21 a of the distal collar 21 by a firstdistance d1. As shown in the figures, according to some implementationsthe distal collar 21 includes a curved/rounded atraumatic end 21 b.

When the retrieval device 20 is in an unconstrained rest position, asshown in FIGS. 1A and 1B, the proximal collar 22 is located at a secondaxial position on the elongate wire 10 with the proximal end 21 a of thedistal collar 21 being located a second distance d2 away from the distalend 22 b of the proximal collar 22, the second distance d2 being lessthan the first distance d1. When the retrieval device is in the expandedrest position, the proximal collar 22 is movable along a length of theelongate wire 10 to a third axial position such that the proximal end 21a of the distal collar 21 is located a third distance d3 away from thedistal end 22 b of the proximal collar 22, the third distance d3 beingless than the second distance d2. The shortening of the distance betweenthe proximal and distal collars from the second distance d2 to the thirddistance d3 urges the arch structures 28 to expand radially outwardand/or causes the stiffness of the clot capturing elements 23 toincrease as result of a more pronounced bending of the clot capturingelements. During a removal of a clot in the vasculature of a patient, adistal movement of the proximal collar 22 on the elongate wire 10 isparticularly advantageous. It can result in the arch structures 28 beingurged to radial expand so that they may more firmly press against thearterial wall during the clot retrieval process. A stiffening of theclot capturing elements 23 increases the rigidity of the clot capturingelements 23 making it more difficult for the arch structures 28 toprolapse during the clot retrieval process. In each case, the retrievaldevice's clot capturing capability is enhanced.

According to some implementations, one or both of the distal collar 21and proximal collar 22 is made of a radiopaque material or coated with aradiopaque material that enables its location to be observed underfluoroscopy.

FIG. 3 shows the retrieval device 20 in the deployed state. During use,the retrieval device 20 may be deployed out the distal end of thedelivery catheter 30 by either withdrawing the delivery catheter in aproximal direction while holding the elongate wire 10 fixed or byholding the delivery catheter 30 fixed while distally advancing theelongate wire 10.

As discussed above, the distal collar 21, proximal collar 22 and shapememory elongate clot capture elements 23 of the retrieval device 20 maycomprise a collection of parts that are assembled together or may beformed from a single piece of material. FIGS. 4A-7C are directed toretrieval devices comprised of a collection of parts and FIGS. 8A-19Bare directed to retrieval devices of unitary construction (i.e. madefrom a single piece of material).

FIGS. 4A and 4B respectively show a proximal end view and across-sectional side view of a distal collar 21 according to oneimplementation. The distal collar 21 includes a central through opening21 c through which the elongate wire 10 passes when the distal collar isfixed to the elongate wire. According to some implementations theproximal end portion 21 d of the collar includes a plurality ofapertures 21 e-j that are radially arranged about the central opening 21c. The apertures 21 e-j may be blind apertures as shown in FIG. 4B ormay comprise through apertures with distal openings. According to someimplementations the apertures 21 e-j are equidistantly spaced around thecentral opening 21 c as shown in FIG. 4A. According to someimplementations, the outer surface of the distal end 21 b of the distalcollar is curved to minimize tissue injury when the retriever 20 ismaneuvered through the vasculature of the patient.

FIGS. 5A, 5B and 5C respectively show a proximal end view, distal endview and cross-sectional side view of the proximal collar 22 accordingto some implementations. The proximal collar 22 includes a centralthrough opening 22 c through which the elongate wire 10 passes when theproximal collar is mounted on the elongate wire in a slideable manner.According to some implementations the distal end portion 22 d of thecollar includes a plurality of apertures 22 e-j that are radiallyarranged about the central opening 22 c. The apertures 22 e-j may beblind apertures as shown in FIG. 5C or may comprise through aperturesthat extend through the entire length of the collar. According to someimplementations the apertures 22 e-j are equidistantly spaced around thecentral opening 22 c as shown in FIG. 5B. According to someimplementations, the proximal end 22 a of the proximal collar 22 iscurved as shown in FIG. 5D for the purpose of minimizing tissue injurywhen the retriever 20 is maneuvered through the vasculature of thepatient.

In the examples of FIGS. 4A-B and 5A-D each of the proximal and distalcollars 22 and 21 respectively possesses six apertures 22 e-j and 21 e-jthat are configured to respectively receive the proximal ends 23 a anddistal ends 23 b of six shape memory elongate clot capturing elements 23e-j as shown in FIG. 6. According to some implementations the shapememory elongate clot capturing elements are fixed inside the aperturesof the proximal and distal collars by use of an adhesive or other meansas discussed above.

Throughout the present disclosure the example retrievers are shown topossess five or six shape memory elongate clot capturing elements. It isimportant to note that the retrievers may have fewer or more than fiveor six shape memory elongate clot capturing elements.

FIG. 7 shows the shape memory elongate clot capturing elements 23 e-jfixed to the distal and proximal collars 21 and 22 depicted in FIGS. 4Band 5D. According to some implementations the shape memory elongate clotcapturing elements 23-j are made of Nitinol and are shape-set in theirrespective rest state configurations as shown in FIGS. 1A and 1B byheating the clot capturing elements above their martensitictransformation temperature. Thereafter, when the clot capturing elements23 are radially constrained and thereafter unconstrained theyautomatically aspire to assume their expanded rest states.

Shaping of the clot capturing elements 23 to assume their expanded reststates may include applying a distal force DF to the proximal collar 22and/or a proximal force PF to the distal collar 21 as shown in FIG. 7Awhile rotating one or both of the distal and proximal collars withrespect to one another in the clockwise or counter-clockwise direction.Alternatively or in conjunction with aforesaid shaping method, the clotcapturing elements 23 may be constrained in their expanded rest stateconfigurations using a specially designed fixture. In either case, theclot capturing elements 23 may be heat treated as discussed above tolock them in their expanded rest state configurations.

As shown in FIG. 7B, upon the distal force DF being applied to theproximal collar 22 and/or upon a proximal force PF being applied to thedistal collar 21, an inversion occurs as the proximal collar 22 is movednearer to the distal collar 21, resulting in the outer peripheralsurface 22 k of the proximal collar 22 being at least partiallysurrounded by bent portions of the clot capturing elements 21 e j.According to one implementation, during or after the inversion, one orboth of the distal collar 21 and proximal collar 22 are rotated withrespect to the other to cause the clot retrieval elements to assume anarched configuration as shown in FIG. 7C with at least portions ofadjacent arched structures overlapping with one another.

According to some implementations, when the retrieval device 20 has beenformed into its expanded rest state, it is mounted to the elongate wire10 and is thereafter stored in a radially constrained state inside, forexample, a peel-away sheath. During a subsequent clot removal process,the retrieval device 20 is loaded into the delivery catheter 30 in itsradially constrained state and made ready for deployment outside thedelivery catheter into the vasculature of the patient.

FIGS. 19A-D illustrate a method through which a clot 52 may be removedfrom an arterial passageway 50 of a patient. The process typicallyincludes the delivery of a guidewire across the clot 52 and a subsequentadvancement of the delivery catheter 30 over the guidewire so that adistal end portion of the delivery catheter resides distal to the clot52. With the delivery catheter in place, the retrieval device 20 isloaded into the delivery catheter 30 as described above. According tosome implementations, the retrieval device 20 is positioned in thedistal end portion of the delivery catheter 30 such that only its distalcurved end 21 b protrudes from the distal end 35 of the deliverycatheter 30 as shown in FIG. 19A. Thereafter, the retrieval device 20 isdeployed from the delivery catheter 30 as shown in FIG. 19B. Asdiscussed above, the retrieval device 20 may be deployed out the distalend of the delivery catheter 30 by either withdrawing the deliverycatheter in a proximal direction while holding the elongate wire 10fixed or by holding the delivery catheter 30 fixed while distallyadvancing the elongate wire 10.

When in the deployed state inside the passageway 50 of the patient, thearched clot capturing elements 23 of the retrieval device 20 pressagainst the arterial wall 54 of the vessel. (Note that when theretrieval device is deployed inside the arterial passageway of thepatient it is sized not achieve its expanded rest state as a result ofits maximum rest state diametric dimension being sized greater than thediameter of the arterial passageway.) After the retrieval device 20 isdeployed inside the passageway 50, the delivery catheter 30 is withdrawnas shown in FIG. 19C with the retrieval device 20 made ready to bepulled proximally to engage the clot 52. As shown in FIG. 19C, justprior to the retrieval device 20 engaging the clot 52, the distal end 22b of the proximal collar 22 is spaced apart from the proximal end 21 aof the distal collar 21 by a distance A. According to someimplementations, as the retrieval device 20 is pulled proximally intothe clot 52, the proximal collar 22 moves distally closer to the distalcollar 21 such that the distal end 22 b of the proximal collar 22 isspaced apart from the proximal end 21 a of the distal collar 21 by adistance B that is less than the distance A as shown in FIG. 19D. Theadvantages associated with the distal movement of the proximal collar 22on the elongate wire 10 during clot capture are discussed above.

Upon the clot 52 being captured by the retrieval device 20, removal ofthe clot may be accomplished, at least in part, by the elongate wire 10being pulled proximally to move the clot to a mouth of an aspirationcatheter or into the delivery catheter 30.

In some implementations the clot capturing elements 23 of retrievaldevice 20 are configured to sweep along the arterial wall 54 to whichthe clot is attached during the removal process to cause the clot, orremnants of the clot, to be moved centrally towards the center of theaffected vessel 50.

In the implementations of FIGS. 1A and 19A-D the clot retrieval assemblyincludes a single retrieval device 20. According to otherimplementations the retrieval assembly includes multiple retrievaldevices spaced apart along the axial length of the elongate wire 10. Inuse, the two or more retrieval devices are each deployed distal to theclot 52. The use of two or more retrieval devices allows remnants of theclot 52 not captured by a proximally disposed retrieval device to becaptured by a distally disposed retrieval device. FIG. 1D shows anexemplary retrieval assembly having three retrieval devices 31, 32 and33 in their expanded rest states disposed along a length of a distal endportion of the elongate wire 10. According to some implementations theretrieval devices 31, 32 and 33 are spaced apart and configured suchthat when they are stored in their radially constrained state inside asheath or inside the delivery catheter 30, the slideable proximal collar33 a of retrieval device 33 is located distal to the fixed distal collar32 b of retrieval device 32 and the slideable proximal collar 32 a ofretrieval device 32 is located distal to the fixed distal collar 31 b ofretrieval device 31. In the example of FIG. 1D, retrieval device 32 isspaced equidistantly between retrieval devices 31 and 33. According toanother implementation retrieval device 32 is located nearer toretrieval device 31 than to retrieval device 33. According to anotherimplementation the retrieval device 32 is located nearer to retrievaldevice 33 than to retrieval device 31.

According to some implementations the elongate wire 10 has a length ofabout 200 centimeters and a diameter of between about 0.01 and 0.014inches. The term “about” when used in conjunction with describing adimensional characteristic herein denotes the stated dimension ±10%.(For example, the statement of the elongate wire 10 having a length ofabout 200 centimeters means a length of between 180 to 220 centimeters.)According to some implementations the delivery catheter 30 has a lengthof about 150 centimeters and an inner diameter of about 0.027 inches.According to some implementations the retrieval device 20 has a radialconstrained length of between about 16 to 30 millimeters and a length ofbetween about 8 to 15 millimeters when the retrieval device in theexpanded rest state. When the retrieval device 20 is in the expandedrest state, the maximum diametric dimension of the expanded device isbetween about 3 to 6 millimeters. According to some implementations theshape memory elongate clot capturing elements 23 have a diameter ofbetween about 0.0002 to 0.0008 inches. (It is important to note that theaccompanying figures are not drawn to scale.)

As discussed above, according to some implementations the retrievaldevice 20 is of a unitary construction with the proximal collar 22,distal collar 21 and clot capturing elements 23 being made from a singlepiece of material. According to some implementations the single piece ofmaterial is a Nitinol tube.

FIGS. 8A-D illustrate a method of making a retrieval device according toone implementation. According to some implementations the methodincludes laser cutting a Nitinol tube 60 to form a plurality ofcircumferentially spaced-apart longitudinally slots 61 to form aplurality of spaced-apart elongate clot capturing elements 62 thatextend continuously (i.e. without any breaks or interruptions) along asubstantial length L1 of the tube 60. FIG. 8B shows the slotted tube 60of FIG. 8A as if it were cut along its length and laid flat on asurface.

The slots 61 have proximal ends 63 that are spaced a distance away fromthe proximal end 65 of tube 60 in order to form the proximal collar 22.Likewise, the slots 61 have a distal end 64 that is spaced a distanceaway from the distal end 66 of tube 60 in order to form the distalcollar 21. The length distance L2 between the proximal and distal ends63 and 64 of the slot are thus less than the length L1 of the tube 60.Each of the length distances L1 and L2 is a straight line distance thatruns parallel to the longitudinal axis 164 of tube 160 as shown in FIG.8B. According to some implementations length L2 is at least 50% thelength L1, and preferably at least 70% the length L1.

After the formation of the slots 61, the tube 60 may be polished toremove slag (oxides) formed during the laser cutting process.Thereafter, the device may be manipulated like that described above inconjunction with the implementations of FIGS. 7A-C to cause the clotcapturing elements 62 to assume a bent configuration as shown in FIGS.8C and 8D. According to one method, the retrieval device is formed byapplying a distal force DF to the proximal collar 22 and/or applying aproximal force PF to the distal collar 21 as shown in FIG. 8A to causean inversion of the clot capturing elements 62 at a proximal end portionof the device. Simultaneously with applying one or both of the distalforce DF and proximal force PF, or at a time after the inversion hasoccurred, one or both of the distal collar 21 and proximal collar 22 maybe rotated clockwise or counterclockwise with respect to other to causeat least some of the clot capturing elements 62 a-e to assume an archedconfiguration. FIG. 8D is a proximal end view of the retrieval deviceshowing the clot capturing elements 62 in their arched configurations.According to some implementations at least some of the arched structures72 overlap with one another as shown in FIG. 8D. According to someimplementations the length of the retrieval device 20 in its expandedrest state is 40% to 70% the pre-inversion length of the tube 60.

In order to shape-set the clot capturing elements 62 into theirrespective expanded rest state configurations as shown in FIGS. 8C and8D, the clot capturing elements are heat treated in their rest stateconfigurations so that when they are radially constrained and thereafterunconstrained they are automatically urged towards their expanded reststates. As discussed above, shaping the clot capturing elements 62 mayinclude applying a distal force DF to the proximal collar 22 and/or aproximal force PF to the distal collar 21 while simultaneously or laterrotating one or both of the distal and proximal collars with respect toone another in the clockwise or counter-clockwise direction.Alternatively or in conjunction with aforesaid shaping method, the clotcapturing elements 62 may be constrained in their expanded rest stateconfigurations using a specially designed fixture. In either case, theclot capturing elements 62 are heat treated to lock them in theirexpanded rest state configurations.

According to some implementations, a cylindrical collar 70 like thatshown in FIG. 11 is fitted into one or both of the annular openings 67and 68 of the distal and proximal collars 21 and 22. The cylindricalcollar 70 includes a central through opening 71 that has a smallerdiameter than the diameter of the annular through openings 67 and 68.The smaller diameter opening 71 enables the retrieval device 20 to bemore centrally located on the elongate wire 10 and makes for a smootherand more controlled sliding action of the proximal collar 22 on theelongate wire 10 as the retrieval device transitions from its radiallyconstrained state to its expanded rest state and also when the retrievaldevice transitions from its expanded rest state to its expanded stressedstate. According to some implementations the central through opening 71of collar 70 has an inner diameter that is 5% to 20% greater than theouter diameter of the elongate wire 10. FIG. 8D shows the cylindricalcollar 70 located in the annular through opening 68 of the proximalcollar 22. The collar 70 may be placed in one or both of the proximaland distal collars of all retrieval devices disclosed and contemplatedherein that are made from a slotted tube.

According to other implementations the slots 61 are cut such that theproximal and distal end sections 62 a and 62 b of the clot capturingelements 62 have different widths with the width of the distal endsections 62 b being greater than the width of the proximal end sections62 a as shown in FIG. 8E. (The proximal end sections 61 a of the slots61 having a greater width than the width of the distal end section 61 bof the slots 61.) The provision of the distal end sections 62 b having agreater width results in smaller gaps existing between them when theresultant retrieval device is in an expanded/deployed state. Thisadvantageously impedes to a greater extent the passage of dislodged clotfragments across the retrieval device during a clot retrieval procedure.

The formation of the inverted part of the retrieval device requires aninitial buckling or outward bending of the clot capturing elements 62somewhere along their length. As shown in FIGS. 9A and 9B, the slottedtube 60 may be provided with a reduced wall thickness region 69somewhere along its length in order to control the location of theinitial buckling or outward bending. The reduced wall thickness region69 may take on any of a variety of shapes that result in an initialbuckling or bending along the reduced wall thickness region of the tubewhen the distal force DF and/or proximal force PF is applied to theproximal and distal ends of the tube 60 like that shown in FIG. 8A.

FIG. 9A shows the Nitinol tube 60 prior to the slots 61 being formedtherein. The tube 60 is cut to form a cylindrical recess 76 in its outercylindrical surface 75. Thereafter, the slots 61 are formed in the tubeas shown in FIGS. 8A and 8B. FIG. 9B shows the tube 60 of FIG. 9A in aflattened state (as if the tube cut were along its length and laid flaton a surface) after the formation of the slots 61. As shown if FIG. 9B,each of the clot capturing elements 62 possesses a zone of reduced wallthickness 69. FIG. 9B shows an implementation wherein the recesses 76formed in the clot capturing elements 62 have a rectangular profile andFIG. 9C shows an implementation wherein the recesses 76 formed in theclot capturing elements 62 have a curved profile such as, for example, asemi-circular profile or a U-shaped profile.

According to some implementations the zones of reduced wall thickness 69are located nearer the distal end 66 of the slotted tube than to theproximal end 65 as shown in FIG. 9B.

According to some implementations the recess 76 is cut in the tube 60 toreduce the wall thickness of the tube in the recessed area by 5-30% andpreferably by 10-20%.

In the implementations of FIGS. 8A-D and 9A-C the slots 61 are cut toform clot capturing elements 62 that are each arranged parallel to thelongitudinal axis 77 of the tube 60 along their entire length. As willbe disclosed in more detail below, the slots 61 may but cut to form clotcapturing elements with different geometries and/or with differentorientations.

FIGS. 10A-E illustrate a method for making a retrieval device accordingto another implementations. According to some implementations the methodincludes laser cutting a Nitinol tube 80 to form a plurality ofcircumferentially spaced-apart longitudinally slots 81. Formed betweenthe slots 81 are a plurality of elongate clot capturing elements 82 thatextend continuously (i.e. without any breaks or interruptions) along asubstantial length of the tube 80. According to some implementations theclot capturing elements 82 have a length L2 that is greater than 50% thelength L1 of the slotted tube 80. According to other implementations theclot capturing elements 82 have a length L2 that is greater than 70% ofthe length L1 of the slotted tube 80. Each of the length distances L1and L2 is a straight line distance that runs parallel to thelongitudinal axis 145 of tube 80.

The proximal ends 86 of the slots 81 are spaced a distance away from theproximal end 83 of the tube 80 and the distal ends 87 of the slots 81are spaced a distance away from the distal end 84 of the tube 80 torespectively form the proximal and distal collars 22 and 21. FIG. 10Bshows the slotted tube 80 of FIG. 10A as if it were cut along its lengthand laid flat on a surface.

As discussed above, the slots 81 are cut to form between them theplurality of clot capturing elements 82. The entirety of the lengths ofslots 81 are not cut in a singular straight path. Instead, each slot iscut to produce clot capturing elements 82 having a straight proximalsection 82 a and a straight distal section 82 b that arecircumferentially offset from one another. According to someimplementations, as shown in FIG. 10B, the clot capturing elements 82include an inflection 85 that connects the distal ends of the straightproximal sections 82 a to the proximal ends of the straight distalsections 82 b. According to some implementations the inflections 85comprise straight segments arranged at an angle with respect to each ofproximal and distal sections 82 a and 82 b of the clot capturingelements 82 as shown in FIG. 10B. According to other implementations theinflections 85 comprise curved segments that may bend in a clockwise orcounter-clockwise direction. The slots 81, clot capturing elements 82and inflections 85 are configured and arranged such that when a distalforce DF is applied to the proximal collar 22 and/or a proximal force PFis applied to the distal collar 21, the tube 80 begins to bulge at oraround the location of the inflections 85 as shown in FIG. 10C.According to some implementations, the inflections 85 are configured tocause the proximal collar 22 to rotate with respect to the distal collar21 (such as when the inflections 85 helically bend) as the proximal anddistal collars are moved nearer to one another as shown in FIG. 10D.

As shown in FIG. 10D, as the distal force DF and/or proximal force PFcontinues to be applied to the tube, an inversion of the clot capturingelements 82 occurs within a proximal end portion of the tube while atthe same time each of the clot capturing elements 82 continue to bend toassume an arched configuration as shown in FIG. 10E. If necessary, oneor both of the distal and proximal collars 21 and 22 may be rotated withrespect to the other during or after the inversion process so that theclot capturing elements assume their arched configurations with adjacentarches 74 preferably overlapping one another as shown in FIG. 10E.Alternatively or in conjunction with the aforesaid shaping method, theclot capturing elements 82 may be constrained in their desired expandedrest state using a specially designed fixture. When the clot capturingelements 82 and collars 21 and 22 are properly oriented with respect toone another, the unit is heat treated to shape-set the resultantretrieval device in its expanded rest state. According to someimplementations the length of the resultant retrieval device 20 in itsexpanded rest state is 50% to 70% the pre-inversion length of the tube80.

According to some implementations zones of reduced wall thickness, likethose discussed above, may be formed along a section of the clotcapturing elements 82 to assist in inducing the proximal end portion ofthe tube 80 to invert. According to some implementations, each of theinflections 85 is provided with a zone of reduced wall thickness. Insuch instances, the zone of reduced wall thickness may span the entirelength of the inflections or less than the entire length. In the lattercase, the zone of reduced wall thickness may be located within amid-section, proximal end section or distal end section of theinflection.

FIG. 12 depicts a Nitinol tube 90 that has been cut and laid flat on asurface. The tube 90 has a length L1 and includes a plurality ofcircumferentially spaced-apart longitudinally slots 91 that are cut intothe tube 90 to form a plurality of elongate clot capturing elements 92that extend continuously along a substantial length of the tube 90.According to some implementations the clot capturing elements have alength L2 that is greater than 50% of the length L1 of the slotted tube90. According to other implementations the clot capturing elements havea length L2 that is greater than 70% of the length L1 of the slottedtube 90. The proximal ends 88 of slots 91 are spaced a distance awayfrom the proximal end 93 of the tube 90 and the distal ends 89 of slots91 are spaced a distance away from the distal end 94 of the tube 90 torespectively form the proximal and distal collars 22 and 21.

In the example of FIG. 12, each of the slots 91 respectively includes aflared portion 95 that creates in each of the clot capturing elements 92a zone of reduced width 96. On each side of the zones of reduced width96 the clot capturing elements 92 include a proximal section 92 a and adistal section 92 b that in the embodiment of FIG. 12 have a same widthW1. In the example of FIG. 12 each of the zones of reduced width 96comprises an area of minimum width W2 located in a mid-section thereof.According to some implementations width W2 is 5-25% less than width W1.

According to some implementations the proximal and distal sections 92 aand 92 b of the clot capturing elements 92 have different widths, withthe width of the distal section 92 b being greater than the width of theproximal section 2. According to some implementations the width of oneor both of the proximal and distal sections 92 a and 92 b may vary alongtheir lengths with the proximal section having a maximum width dimensionalong its length and the proximal section having a maximum widthdimension along its length with the maximum width dimension of thedistal section 92 b being greater than the maximum width dimension ofthe proximal section 92 a.

The slots 91, clot capturing elements 92 and zones of reduced width 96are configured and arranged such that when a distal force DF is appliedto the proximal collar 22 and/or a proximal force PF is applied to thedistal collar 21, the tube 90 begins to bulge at or around the locationof the zones of reduced width 96 to assist in facilitating an inversionof the clot capturing elements within a proximal end portion of the tube90. According to other implementations, one or both of the first andsecond sections 92 a and 92 b of the clot capturing elements are notarranged parallel to the longitudinal axis of the tube 90 but mayinstead be curved (e.g. arranged in a helical pattern) about thelongitudinal axis of the tube 90 as shown in FIGS. 15A-17B below.

In the example of FIG. 12 the width of the flared portions varies alongits length in a linear fashion as a result of the flared portions beingbound by ramped straight wall segments 98 a, 98 b, 98 c and 98 d.According to other implementations the flared portions are bound bycurved wall segments that result in a non-linear width variation alongthe length of the flared portions. In the implementation of FIG. 12,proximal wall segments 98 a and 98 c diverge distally away from oneanother and distal wall segments 98 b and 98 d converge distally towardone another. According to some implementations the flared portion 95 ofthe slots 91 are shaped such that the resultant clot capturing elements92 take the form of an hourglass along a portion of their lengths asshown in FIG. 12.

According to some implementations the zones of reduced width 96 of theclot capturing elements 92 are located nearer the proximal end 93 of theslotted tube 90 than to the distal end 94 as shown in FIG. 12. Accordingto other implementations the zones of reduced width are located nearerthe distal end 94 of the slotted tube 90 than to the proximal end 93.

As with the previously disclosed implementations, during or after aninversion of the proximal end portions 92 a of the clot capturingelements 92 around the proximal collar 21, one or both of the distalcollar 21 and proximal collar 22 may be rotated with respect to theother to cause a formation of a retrieval device similar to thatdepicted in FIGS. 8C and 8D.

Alternatively or in conjunction with the aforesaid shaping method, theclot capturing elements 92 may be constrained in their desired expandedrest state using a specially designed fixture. In any event, when theresultant retrieval device has been formed to assume its desiredexpanded rest state, the manufacturing process is followed by a definedheat treatment to shape-set the resultant clot retrieval device in itsexpanded rest state. According to some implementations the length of theresultant retrieval device in its expanded rest state is 50% to 70% thepre-inversion length of the tube 90.

FIGS. 13A and 13B depict a variant of the slotted tube of FIG. 12. FIGS.13A and 13B respectively show a slotted Nitinol tube 100 comprising aplurality of slots 101. Interposed between the slots 101 are clotcapturing elements 102. FIG. 13A shows the tube 100 in its cylindricalconfiguration. FIG. 13B shows the slotted tube 100 as if it were cutalong its length and laid flat on a surface. Like the example of FIG.12, one or more or all of the slots 101 comprise flared portions 105that result in the formation of zones of reduced width 106 along aportion of the length of the clot capturing elements 102. The flaredportions 105 of FIGS. 13A-B differ from the flared portions 96 of FIG.12 in both size and shape, being shorter in length and comprising a morerectangular shape.

FIGS. 14A and 14B show a slotted Nitinol tube 120 used for making aretrieval device similar to those depicted in FIGS. 10D and 10E. FIG.14A shows the tube 120 in its cylindrical configuration. FIG. 14B showsthe tube 120 as if it were cut along its length and laid flat on asurface. The tube 120 has a length L1 between its proximal and distalends 130 and 131.

The slotted tube 120 includes a plurality of circumferentiallyspaced-apart slots 121 that extend continuously across a substantiallength of the tube 120. According to some implementations each of theslots 121 has a length L2 that is at least 50% the length L1 of the tube120, and preferably a length L2 that is at least 70% the length of thetube 120. As shown in FIG. 12, each of the length distances L1 and L2 isa straight line distance that runs parallel to the longitudinal axis 129of tube 120.

Each of the slots 121 includes a proximal segment 121 a and a distalsegment 121 b that are circumferentially offset from one another andjoined together at their respective overlapping distal and proximal ends123 and 124 by a lateral passage 128. Circumferentially adjacent slots121 form between them a clot capturing element 122 that includescircumferentially offset proximal and distal segments 122 a and 122 b ofa first width W1 that are joined by a reduced width segment 127 having awidth W2 that is less than the width W1. According to someimplementations the width W2 is 5-50% the width W1 while according toother implementations the width W2 is 5-20% the width W1.

According to some implementations the reduced width segments 127 arelocated nearer the distal end 131 of the slotted tube 120 than to theproximal end 130.

The proximal end 123 of the slots 121 are spaced a distance away fromthe proximal end 130 of the tube 120 and the distal end 126 of the slots121 are spaced a distance away from the distal end 131 of the tube 120to respectively form the proximal and distal collars 22 and 21.

As shown in FIG. 14B, each of the clot capturing elements 122 includes azone 140 in which the reduced width segment 127 coincides with a changeof trajectory of the clot capturing element. As a result of the clotcapturing element configurations, when an initial distal force DF isapplied to the proximal collar 22 and/or an initial proximal force PF isapplied to the distal collar 21, the tube 120 begins to bulge at oraround the location of the zones 140.

As the distal force DF and/or proximal force PF continues to be appliedto the tube 120, an inversion of the clot capturing elements 122 occurswithin a proximal end portion of the tube similar to that shown in FIG.10D. If necessary, during or after the inversion, one or both of thedistal and proximal collars 21 and 22 may be rotated with respect to theother to cause the clot capturing elements 122 to assume a desiredarched configuration with adjacent arches preferably overlapping oneanother as shown in FIG. 10E.

Alternatively or in conjunction with the aforesaid shaping method, theclot capturing elements 122 may be constrained in their desired expandedrest state using a specially designed fixture. In any event, when theresultant retrieval device has been formed to assume its desiredexpanded rest state, the manufacturing process is followed by a definedheat treatment to shape-set the resultant clot retrieval device in itsexpanded rest state. According to some implementations the length of theresultant retrieval device in its expanded rest state is 50% to 70% thepre-inversion length of the tube 120.

FIGS. 15A-B illustrate a slotted tube 150 from which a retrieval devicelike those depicted in FIGS. 10D and 10E may be made. FIG. 15A shows theslotted tube in its cylindrical configuration, FIG. 15B shows the tube150 as if it has been cut along its length and laid flat on a surface.The tube has a length L1 between its proximal and distal ends 156 and157.

Tube 150 includes a plurality of circumferentially spaced-apart slots151 that form between them a plurality of circumferentially spaced-apartclot capturing elements 152. The tube 150 includes a proximal endportion 150 a and a distal end portion 150 b each having slots 151 cuttherein to produce between circumferentially adjacent slots clotcapturing elements 152. In the proximal end portion 150 a of the tube150 the clot capturing elements include a proximal end section 152 athat curves around the longitudinal axis 154 of the tube 150 in, forexample, a helical fashion. In the distal end portion 150 b of the tube150 the clot capturing elements include a distal end section 152 b thatis arranged substantially parallel to the longitudinal axis 154.

According to some implementations the slots 151 include a flared portion155 that produces in the clot capturing elements 152 a zone of reducedwidth 153 that join the proximal and distal sections 152 a and 152 b.According to some implementations the zones of reduced width 153 arearranged non-parallel to the longitudinal axis 154 of the tube 150 andalso non-parallel to each of the proximal and distal sections 152 a and152 b of the clot capturing elements 152 as best seen in FIG. 15B.

According to some implementations the zones of reduced width 153 arelocated nearer the distal end 157 of the slotted tube 150 than to theproximal end 156.

According to some implementations, each of the helical proximal endsection 152 a and a straight distal end section 152 b of the clotcapturing elements 152 have a same first width W1 and the zone ofreduced width 153 has a second width W2 that is less than the firstwidth W1. According to some implementations the width W2 is 5-50% thewidth W1, while according to other implementations the width W2 is 5-20%the width W1.

According to other implementations the slots 151 are cut such that theproximal and distal end sections 152 a and 152 b of the clot capturingelements 152 have different widths with the width W3 of the distal endsections 152 b being greater than the width W4 of the proximal endsections 152 a as shown in FIG. 15C. The provision of the distal endsections 152 b having a greater width results in smaller gaps existingbetween them when the resultant retrieval device is in anexpanded/deployed state. This advantageously impedes to a greater extentthe passage of dislodged clot fragments across the retrieval deviceduring a clot retrieval procedure.

With continued reference to FIGS. 15A-B, the slots 151 have proximalends 151 a that are spaced a distance away from the proximal end 156 oftube 150 in order to form the proximal collar 22. Likewise, the slots151 have a distal end 151 b that is spaced a distance away from thedistal end 157 of tube 150 in order to form the distal collar 21. Thelength distance L2 between the proximal and distal ends 151 a and 151 bof the slot are thus less than the length L1 of the tube 150. Each ofthe length distances L1 and L2 is a straight line distance that runsparallel to the longitudinal axis 154 of tube 150. According to someimplementations length L2 is at least 50% the length L1, and preferablyat least 70% the length L1.

As disclosed above, according to some implementations the clot capturingelements 152 include a zone of reduced width 153 that coincides with achange of trajectory of the clot capturing elements. Due to such clotcapturing element configurations, when an initial distal force DF isapplied to the proximal collar 22 and/or an initial proximal force PF isapplied to the distal collar 21, the tube 150 begins to bulge at oraround the location of the zones of reduced width 153. By virtue of thehelical nature of the proximal end section 152 a of the clot capturingelements 152, as the distal and proximal collars 21 and 22 are broughtcloser together by the application of the proximal and/or distal forces,the proximal collar 22 rotates with respect to the distal collar 21.

As the distal force DF and/or proximal force PF continues to be appliedto the tube 150, an inversion of the clot capturing elements 152 occursat least within the proximal end portion 150 a of the tube similar towhat is shown in FIG. 10D, while at the same time each of the clotcapturing elements 152 continues to bend to produce, for example, archedelements like those shown in FIG. 10D with adjacent arches preferablyoverlapping one another as shown in FIG. 10E.

Alternatively or in conjunction with the aforesaid shaping method, theclot capturing elements 152 may be constrained in their desired expandedrest state using a specially designed fixture. In any event, when theresultant retrieval device has been formed to assume its desiredexpanded rest state, the manufacturing process is followed by a definedheat treatment to shape-set the resultant clot retrieval device in itsexpanded rest state. According to some implementations the length of theresultant retrieval device in its expanded rest state is 50% to 70% thepre-inversion length of the tube 150.

FIGS. 16A-B illustrate a slotted tube 160 from which a retrieval devicelike those depicted in FIGS. 10D and 10E may be made. FIG. 16A shows theslotted tube in its cylindrical configuration, FIG. 16B shows the tube160 as if it has been cut along its length and laid flat on a surface.The tube has a length L1 between its proximal and distal ends 166 and167.

Tube 160 includes a plurality of circumferentially spaced-apart slots161 that form between them a plurality of circumferentially spaced-apartclot capturing elements 162. The tube 160 includes a proximal endportion 160 a and a distal end portion 160 b each having slots 161 cuttherein to produce between circumferentially adjacent slots clotcapturing elements 162. In the proximal end portion 160 a of the tube160 the clot capturing elements 162 include a proximal end section 162 athat curves around the longitudinal axis 164 of the tube 160 in a firstdirection (e.g. counter clockwise direction) and a distal end section162 b that curves around the longitudinal axis 164 of the tube 160 in asecond direction (e.g. clockwise direction) opposite the firstdirection.

According to some implementations the slots 161 include a flared portion165 that produces in the clot capturing elements 162 a zone of reducedwidth 163 that join the proximal and distal sections 162 a and 162 b.According to some implementations the zones of reduced width 163 arearranged parallel to the longitudinal axis 164 of the tube 160.

According to some implementations the zones of reduced width 163 arelocated nearer the distal end 167 of the slotted tube 160 than to theproximal end 166.

According to some implementations, each of the proximal end section 162a and distal end section 162 b of the clot capturing elements 162 have asame first width W1 and the zone of reduced width 163 has a second widthW2 that is less than the first width W1. According to someimplementations the width W2 is 5-50% the width W1, while according toother implementations the width W2 is 5-20% the width W1.

According to other implementations the slots 161 are cut such that theproximal and distal end sections 162 a and 162 b of the clot capturingelements 162 have different widths with the width of the distal endsections 162 b being greater than the width of the proximal end sections162 a. The provision of distal end sections 162 b having a greater widthresults in smaller gaps existing between them when the resultantretrieval device is in an expanded/deployed state. This advantageouslyimpedes to a greater extent the passage of dislodged clot fragmentsacross the retrieval device during a clot retrieval procedure.

With continued reference to FIGS. 16A-B, the slots 161 have proximalends 161 a that are spaced a distance away from the proximal end 166 oftube 160 in order to form the proximal collar 22. Likewise, the slots161 have a distal end 161 b that is spaced a distance away from thedistal end 167 of tube 160 in order to form the distal collar 21. Thelength distance L2 between the proximal and distal ends 161 a and 161 bof the slot are thus less than the length L1 of the tube 160. Each ofthe length distances L1 and L2 is a straight line distance that runsparallel to the longitudinal axis 164 of tube 160. According to someimplementations length L2 is at least 50% the length L1, and preferablyat least 70% the length L1.

As disclosed above, according to some implementations the clot capturingelements 162 include a zone of reduced width 163 that coincides with achange of trajectory of the clot capturing elements. Due to such clotcapturing element configurations, when an initial distal force DF isapplied to the proximal collar 22 and/or an initial proximal force PF isapplied to the distal collar 21, the tube 160 begins to bulge at oraround the location of the zones of reduced width 163. By virtue of thecurved nature of the proximal end section 162 a of the clot capturingelements 162, as the distal and proximal collar 22 is brought axiallycloser to the distal collar 21, one or both of the proximal and distalcollars 22 and 21 rotates with respect to the other.

As the distal force DF and/or proximal force PF continues to be appliedto the tube 160, an inversion of the clot capturing elements 162 occursat least within the proximal end portion 160 a of the tube similar towhat is shown in FIG. 10D, while at the same time each of the clotcapturing elements 162 continues to bend to produce arched elements withadjacent arches preferably overlapping one another.

Alternatively or in conjunction with the aforesaid shaping method, theclot capturing elements 162 may be constrained in their desired expandedrest state using a specially designed fixture. In any event, when theresultant retrieval device has been formed to assume its desiredexpanded rest state, the manufacturing process is followed by a definedheat treatment to shape-set the resultant clot retrieval device in itsexpanded rest state. According to some implementations the length of theresultant retrieval device in its expanded rest state is 50% to 70% thepre-inversion length of the tube 160.

FIGS. 17A-B illustrate a slotted tube 170 from which a retrieval devicelike those depicted in FIGS. 10D and 10E may be made. FIG. 17A shows theslotted tube in its cylindrical configuration, FIG. 17B shows the tube170 as if it has been cut along its length and laid flat on a surface.The tube has a length L1 between its proximal and distal ends 176 and177.

Tube 170 includes a plurality of circumferentially spaced-apart slots171 that form between them a plurality of circumferentially spaced-apartclot capturing elements 172. The tube 170 includes a proximal endportion 170 a and a distal end portion 170 b that each have slots 171cut therein to produce between circumferentially adjacent slots the clotcapturing elements 172. In the proximal end portion 170 a of the tube170 the clot capturing elements 172 include a curved proximal endsection 172 a as shown in FIG. 17B comprising a single bend. As alsoshown in FIG. 17B, in the distal end portion 170 b of the tube 170 theclot capturing elements 172 include a curved distal end section 172 bcomprising multiple bends.

According to some implementations the slots 171 include flared portion175 that produces in the clot capturing elements 172 a zone of reducedwidth 173 that joins the proximal and distal end sections 172 a and 172b of the slots 172. According to some implementations the zones ofreduced width 173 are located nearer the distal end 177 of the slottedtube 170 than to the proximal end 176.

According to some implementations, each of the proximal and distal endsection 172 a and 172 b of the clot capturing elements 172 have a samefirst width W1 and the zone of reduced width 173 has a second width W2that is less than the first width W1. According to some implementationsthe width W2 is 5-50% the width W1, while according to otherimplementations the width W2 is 5-20% the width W1.

According to other implementations the slots 171 are cut such that theproximal and distal end sections 172 a and 172 b of the clot capturingelements 172 have different widths with the width of the distal endsections 172 b being greater than the width of the proximal end sections172 a. The provision of distal end sections 172 b having a greater widthresults in smaller gaps existing between them when the resultantretrieval device is in an expanded/deployed state. This advantageouslyimpedes to a greater extent the passage of dislodged clot fragmentsacross the retrieval device during a clot retrieval procedure.

With continued reference to FIGS. 17A-B, the slots 171 have proximalends 171 a that are spaced a distance away from the proximal end 176 oftube 170 in order to form the proximal collar 22. Likewise, the slots171 have a distal end 171 b that is spaced a distance away from thedistal end 177 of tube 170 in order to form the distal collar 21. Thelength distance L2 between the proximal and distal ends 171 a and 171 bof the slot are thus less than the length L1 of the tube 170. As shownin FIG. 17B, each of the length distances L1 and L2 is a straight linedistance that runs parallel to the longitudinal axis 174 of tube 170.According to some implementations length L2 is at least 50% the lengthL1, and preferably at least 70% the length L1.

The zone of reduced width 163 in the clot capturing elements 172coincides with a change of trajectory of the clot capturing elements asa result of being located in a curve of the clot capturing elements. Dueto such clot capturing element configurations, when an initial distalforce DF is applied to the proximal collar 22 and/or an initial proximalforce PF is applied to the distal collar 21, the tube 170 begins tobulge at or around the location of the zones of reduced width 173. Byvirtue of the curved nature of the proximal end section 172 a of theclot capturing elements 172, as the distal and proximal collars 21 and22 are brought closer together by the application of the proximal and/ordistal forces, one or both of the proximal and distal collars 22 and 21rotate with respect to the other.

As the distal force DF and/or proximal force PF continues to be appliedto the tube 170, an inversion of the clot capturing elements 172 occursat least within the proximal end portion 170 a of the tube similar towhat is shown in FIG. 10D, while at the same time each of the clotcapturing elements 172 continues to bend to produce arched elements withadjacent arches preferably overlapping one another. Alternatively or inconjunction with the aforesaid shaping method, the clot capturingelements 172 may be constrained in their desired expanded rest stateusing a specially designed fixture. In any event, when the resultantretrieval device has been formed to assume its desired expanded reststate, the manufacturing process is followed by a defined heat treatmentto shape-set the resultant clot retrieval device in its expanded reststate. According to some implementations the length of the resultantretrieval device in its expanded rest state is 50% to 75% thepre-inversion length of the tube 170.

FIGS. 18A-B illustrate a slotted tube 200 from which a retrieval devicelike those depicted in FIGS. 10D and 10E may be made. FIG. 18A shows theslotted tube in its cylindrical configuration, FIG. 18B shows the tube200 as if it has been cut along its length and laid flat on a surface.The tube has a length L1 between its proximal and distal ends 206 and207.

Tube 200 includes a plurality of circumferentially spaced-apart slots201 that form between them a plurality of circumferentially spaced-apartclot capturing elements 202. The tube 200 includes a proximal endportion 200 a and a distal end portion 200 b that each have slots 201cut therein to produce between circumferentially adjacent slots the clotcapturing elements 202. The slots 201 are cut such that their widthsconstantly vary along their length. As a result, the clot capturingelements 202 disposed between the slots 201 also have a constantlyvarying width along their lengths L2.

In the implementation of FIGS. 18A-B, the clot capturing elements 202include a proximal end section 204 having a proximal end 204 a and adistal end 204 b. The clot capturing elements 202 also include a distalend section 205 having a distal end 205 b and a proximal end 205 a thatcoincides with the distal end 204 b of the proximal end section 204.Each of the distal end sections 205 and distal end sections of the clotcapturing elements are respectively defined by curved wall segments 204c, 204 d and 205 c, 205 d. According to some implementations the curvedwall segments are shaped so that the maximum width locations W1 of theproximal and distal sections 204 and 205 reside at each of theirrespective proximal and distal ends 204 a/b and 205 a/b. According tosome implementations the curved wall segments are shaped to producealong the length of each of the proximal and distal end sections 204 and205 a single minimum width location W2. According to someimplementations the minimum width location W2 of each of the proximaland distal end sections 204 and 205 is disposed equidistantly betweentheir respective proximal and distal ends 204 a, 204 b and 205 a and 205b.

According to some implementations the width W2 is 30-90% the width W1,while according to other implementations the width W2 is 25-80% thewidth W1.

According to some implementations the distal end 204 b of the proximalend section 204 of the clot capturing elements 202 meets with theproximal end 205 a of the distal end section 205 at a point locatednearer the distal end 208 of the tube 200 than to the proximal end 207of the tube. According to other implementations the distal end 204 b ofthe proximal end section 204 of the clot capturing elements 202 meetswith the proximal end 205 a of the distal end section 205 at a pointlocated equidistantly between the proximal and distal ends 207 and 208of tube 200.

With continued reference to FIGS. 18A-B, the slots 201 have proximalends 201 a that are spaced a distance away from the proximal end 207 oftube 200 in order to form the proximal collar 22. Likewise, the slots201 have a distal end 201 b that is spaced a distance away from thedistal end 208 of tube 200 in order to form the distal collar 21. Thelength distance L2 between the proximal and distal ends 201 a and 201 bof the slots is thus less than the length L1 of the tube 200. As shownin FIG. 18B, each of the length distances L1 and L2 is a straight linedistance that runs parallel to the longitudinal axis 209 of tube 200.According to some implementations length L2 is at least 50% the lengthL1, and preferably at least 70% the length L1.

Like with the slotted tube implementations disclosed above, theformation of a clot retrieval device similar in construction to thosedepicted in FIGS. 10D and 10E may be achieved by applying a distal forceDF to the proximal collar 21 and/or proximal force PF to the distalcollar 21 to induce an inversion of at least the proximal end sections204 of the clot capturing elements 202. Also as disclosed above, duringor after the inversion, one or both of the proximal and distal collars22 and 21 may be rotated with respect to one another to cause the clotcapturing elements 202 to achieve a desired arched configurations.Alternatively or in conjunction with the aforesaid shaping method, theclot capturing elements 202 may be constrained in their desired expandedrest state using a specially designed fixture. In any event, when theresultant retrieval device has been formed to assume its desiredexpanded rest state, the manufacturing process is followed by a definedheat treatment to shape-set the resultant clot retrieval device in itsexpanded rest state. According to some implementations the length of theresultant retrieval device in its expanded rest state is 50% to 75% thepre-inversion length of the tube 200.

FIGS. 20A-C illustrate a clot retrieval assembly 300 that includesdistal clot retrieval device 320 and a proximal clot retrieval device340 mounted on an elongate wire 310. In use, the retrieval devices 320and 340 are delivered to the site of an obstruction while being radiallyconstrained inside a delivery catheter 360 as shown in FIG. 20C.

In some implementations distal retrieval device 320 includes a distalcollar 321 fixed stationary to the elongate wire 310, and a proximalcollar 322 that is slideable on the elongate wire 310. Extending betweenthe proximal and distal collars are multiple shape memory elongate clotcapturing elements 323 that are configured to engage the obstructionwhen the distal retrieval device 320 is in an expanded/deployed state asshown in FIGS. 20A and 20B. When the distal retrieval device 320 is anexpanded/deployed state, the shape memory elongate clot capturingelements 323 assume a curved configuration that may be similar to ordifferent than what is shown in FIGS. 20A and 20B.

In some implementations proximal retrieval device 340 includes aproximal collar 342 fixed stationary to the elongate wire 310, and adistal collar 341 that is slideable on the elongate wire 310. Extendingbetween the proximal and distal collars 342 and 341 are multiple shapememory elongate clot capturing elements 343 that are configured toengage the obstruction when the proximal retrieval device 340 is in anexpanded/deployed state as shown in FIGS. 20A and 20B. When proximalretrieval device 340 is an expanded/deployed state, the shape memoryelongate clot capturing elements 343 assume a curved configurationsimilar to or different than what is shown in FIGS. 20A and 20B.

According to some implementations each of the distal and proximalretrieval devices 320 and 340 are constructed from a collection ofindependent parts like those depicted in FIGS. 4A-6. According to otherimplementations, each of the distal and proximal retrieval devices 320and 340 are made from a slotted tube like those discussed above inconjunction with FIGS. 8A-18B.

When the distal retrieval device 320 is deployed from the deliverycatheter 360 to assume an expanded state, it includes a proximalinverted portion 324 and a distal non-inverted portion 325. When thedistal retrieval device 340 is deployed from the delivery catheter 360to assume an expanded state, it includes a distal inverted portion 344and a proximal non-inverted portion 345. As shown in FIG. 20A, accordingto some implementations the distal non-inverted portion 325 of thedistal retrieval device 320 is provided with a permeable cover 327 madeof a biocompatible material. The purpose of the permeable cover 327 isto capture fragments of the clot that may become dislodged during theclot retrieval process. According to some implementations thebiocompatible material is encapsulated polytetrafluoroethylene (ePTFE)with a thickness of 0.0008 to 0.016 inches.

According to some implementations, when the distal retrieval device 320is in its unconstrained expanded rest state, as shown in FIGS. 20A and20B, the shape memory elongate clot capturing elements 323, as viewedfrom a proximal end of the distal retrieval device 320, form a pluralityof arch structures like those shown in FIGS. 7C and FIG. 8D, withadjoining arch structures preferably, but not necessarily, overlappingwith one another.

According to some implementations, when the proximal retrieval device340 is in its unconstrained expanded rest state, as shown in FIGS. 20Aand 20B, the shape memory elongate clot capturing elements 343, asviewed from a distal end of the distal retrieval device 340, form aplurality of arch structures like those shown in FIG. 7C and FIG. 8D,with adjoining arch structures preferably, but not necessarily,overlapping with one another.

FIG. 20C is a side cross-sectional view of the distal end portion of thedelivery catheter 360 showing the distal and proximal retrieval devices320 and 340 radially constrained inside the delivery catheter. Thedistal retrieval device 320 functions like the retrieval device 20discussed above in conjunction with the description of FIGS. 1A-3, beingtransitional between a radially constrained state, an expanded reststate, and an expanded stressed state. The proximal retrieval device 340functions similar to the distal retrieval device 320, but in reversal.

According to some implementations, one or both of the distal collar 321and proximal collar 322 of the distal retrieval device 320 and/or one orboth of the distal collar 341 and proximal collar 342 of the proximalretrieval device 340 are made of a radiopaque material or are coatedwith a radiopaque material that enables their locations to be observedunder fluoroscopy.

In use, the distal end portion of the delivery catheter 360 is delivereddistal to the site of the clot over a guidewire like that shown in FIG.19A. With the delivery catheter in place, the retrieval devices 320 and340 are loaded in their radially constrained state into the deliverycatheter 360 as shown in FIG. 20C. Thereafter, the distal and proximalretrieval devices are deployed distal to the clot by either withdrawingthe delivery catheter in a proximal direction while holding the elongatewire 10 fixed or by holding the delivery catheter 30 fixed whiledistally advancing the elongate wire 10.

When in their deployed states inside the passageway of the patient, thearched structures of the retrieval devices 320 and 340 press against thearterial wall of the vessel. After the retrieval devices 320 and 340 aredeployed, the elongate wire 310 to which the retrieval devices areattached is pulled proximally to first engage the proximal retrievaldevice 340 with the clot to entrap at least a portion of the clotbetween the clot capturing elements 343. After at least a portion of theclot is entrapped in the proximal retrieval device 340, the elongatewire 310 is further advanced proximally to engage the distal retrievaldevice 320 with any remaining portion of the clot. In someimplementations the clot capturing elements 323 of the distal retrievaldevice 320 are configured to sweep along the arterial wall to which theclot is attached to cause the clot, or remnants of the clot, to be movedcentrally towards the center of the affected vessel.

According to some implementations the distal collar 341 of the proximalretrieval device 340 and the proximal collar 322 of the distal retrievaldevice 320 move distally along the elongate wire 310 as the retrievaldevices are pulled proximally through the clot. According to someimplementations the proximal retrieval device 340 may be positionedproximal to the clot and pushed against or into the clot during the clotremoval process. In such instances its distal collar 341 movesproximally along the elongate wire 310 as the retrieval device is pusheddistally into the clot. As discussed above, the movement of the collarson the elongate wire during the clot capturing process stresses the clotcapturing elements, enhancing their ability to entrap the clot.

Upon the clot being captured by one or both of the retrieval devices 320and 340, removal of the clot may be accomplished, at least in part, bythe elongate wire 10 being pulled proximally to move the clot to a mouthof an aspiration catheter or into the delivery catheter 360.

FIG. 21 show a clot capturing assembly that includes distal and proximalretrieval devices 320 and 340 that may be made by any of a number ofmethods, including those disclosed above. The clot capturing assemblydiffers from the assembly of FIG. 20A-C in that the proximal retrievaldevice 340 is axially moveable along a length of the elongate wire 310so that the distance that separates it from the distal retrieval device320 may be varied. In all other respects the distal and proximalretrieval devices function as described above.

As with the implementations of FIGS. 20A-C, distal retrieval device 320is mounted to the elongate wire 310 with its distal collar 321 fixedstationary to the elongate wire and its proximal collar 322 slideable onthe elongate wire. On the other hand, the distal collar 341 and proximalcollar 342 of the proximal retrieval device 340 are both slideable onthe elongate wire 310 with the proximal collar 342 being fixed to adistal end 371 of an elongate hypotube 370 through which the elongatewire 310 passes. A proximal end portion of the hypotube 370 is attachedto a sliding tab 381 located inside a user handle 380. The user handle380 is configured such that when the handle is gripped by the user, theuser's thumb may act on the sliding tab 381 to move the tab in a forwarddirection F or a rearward direction R. With the elongate wire 310 heldstationary, when the tab 381 is moved in the forward direction F, thehypotube 370 is advanced distally to cause the proximal retrieval device340 to move distally along the elongate wire 310 nearer the distalretrieval device 320. Conversely, when the tab 381 is moved in therearward direction R, the hypotube 370 is advanced proximally to causethe proximal retrieval device 340 to move proximally along the elongatewire 310 away from the distal retrieval device 320.

The retrieval devices 320 and 340 are typically delivered to the site ofthe clot through a previously placed delivery catheter 360. FIG. 22shows a side view and FIG. 23 shows a cross-sectional side view of theretrieval devices 320 and 340 radially constrained inside the lumen ofthe delivery catheter 360. When the sliding tab 381 of the user handle380 is in a center position as shown in FIG. 21, the distal and proximalretrieval devices 320 and 340 are separated inside the lumen of thedelivery catheter 360 by a distance D. Prior to deploying one or both ofthe retrieval devices 320 and 340 from the delivery catheter 360, theuser may increase or decrease the distance D between them byrespectively moving the sliding tab 381 in the rearward direction R orthe forward direction F. Upon the proximal retrieval device 340 beingplaced in a desired position with respect to the distal retrieval device320, the sliding tab 381 is locked in position to prevent any axialmovement of the hypotube 370. Thereafter, the distal retrieval device320 is deployed outside the delivery catheter 360 as shown in FIG. 24,and in some instances is followed by a deployment of the proximalretrieval device 340 outside the delivery catheter as shown in FIG. 25A.One or both of the retrieval device 320 and 340 may be deployed out thedistal end of the delivery catheter 360 by either withdrawing thedelivery catheter in a proximal direction while holding the elongatewire 310 fixed or by holding the delivery catheter fixed while distallyadvancing the elongate wire 310.

FIG. 25A shows the distal and proximal retrieval devices 320 and 340deployed outside the delivery catheter 360 and being separated by afirst distance D1. FIG. 25B shows the distal and proximal retrievaldevices 320 and 340 deployed outside the delivery catheter 360 and beingseparated by a second distance D2 that is less than the first distance.

According to some implementations the hypotube 170 has a length of about180 centimeters and an inner diameter of between about 0.010 to 0.016inches.

The following Group A-E clauses disclose in an unlimited way additionalimplementations.

Group A Clauses:

Clause 1. A clot retrieval assembly comprising:

-   -   an elongate wire having a length and a longitudinal axis;    -   a first retrieval device comprising:        -   a distal collar fixed stationary on the elongate wire;        -   a proximal collar being slideable along a portion of the            length of the elongate wire; and        -   a plurality of shape memory elongate clot capturing elements            that each has a proximal end coupled to the proximal collar            and a distal end coupled to the distal collar, each of the            plurality of shape memory elongate capturing elements having            a proximal end portion and a distal end portion;        -   the first retrieval device being configured to automatically            transition from a radially constrained state to an expanded            rest state, in the radially constrained state no portion of            the plurality of shape memory elongate clot capturing            elements is located proximal to the proximal collar and the            proximal collar is located at a first axial position on the            elongate wire proximal to the distal collar and is spaced            apart from the distal collar by a first distance, in the            expanded rest state the proximal collar is located at a            second axial position on the elongate wire proximal to the            distal collar and is spaced apart from the distal collar by            a second distance that is less than the first distance and            at least some of the proximal portions of the plurality of            shape memory elongate clot capturing elements are inverted            around the proximal collar with at least some of the            proximal portions of the plurality of shape memory elongate            clot capturing elements being disposed proximal to the            proximal collar.

Clause 2. The clot retrieval assembly according to clause 1, whereinwhen the first retrieval device is in the expanded rest state theproximal collar is movable distally to a third axial position on theelongate wire proximal to the distal collar and is spaced apart from thedistal collar by a third distance that is less than the second distance.

Clause 3. The clot retrieval assembly according to clause 2, whereinwhen the proximal collar of the first retrieval device is in the thirdaxial position on the elongate wire, the first retrieval device is in anexpanded stressed state.

Clause 4. The clot retrieval assembly according to clause 1, whereinwhen the first retrieval device is in the radially constrained state noportion of each of the plurality of shape memory elongate clot capturingelements bends back on itself.

Clause 5. The clot retrieval assembly according to any of the precedingclauses, wherein the second length is 30% to 60% the first length.

Clause 6. The clot retrieval assembly according to any of the precedingclauses, wherein when the first retrieval device is in the expanded reststate at least some of the plurality of shape memory elongate clotcapturing elements take a zigzag path from the proximal collar to thedistal collar with a first portion of the path extending in a proximaldirection and a second portion of the path extending in a distaldirection.

Clause 7. The clot retrieval assembly according to any of the precedingclauses, wherein when the first retrieval device in the expanded reststate the first retrieval device includes a proximal inverted portionwhere the shape memory elongated clot capturing elements are invertedaround the proximal collar, and a distal non-inverted portion, thedistal non-inverted portion being composed of distal end portions of theshape memory elongate clot capturing elements.

Clause 8. The clot retrieval assembly according to clause 2, whereinwhen the proximal collar is in the second axial position one or more ofthe shape memory elongate clot capturing elements has a first stiffness,and when the proximal collar is in the third axial position the one ormore shape memory elongate clot capturing elements has a secondstiffness greater than the first stiffness.

Clause 9. The clot retrieval assembly according to clause 7, wherein thedistal non-inverted portion of the first retrieval device includes apermeable cover.

Clause 10. The clot retrieval assembly according to any of the precedingclauses, wherein each of the plurality of shape memory elongate clotcapturing elements has a proximal end and a distal end that arerespectively attached to the proximal and distal collars by an adhesive.

Clause 11. The clot retrieval assembly according to any of the precedingclauses, wherein each of the plurality of shape memory elongate clotcapturing elements has a proximal end and a distal end that arerespectively attached to the proximal and distal collars by a solder.

Clause 12. The clot retrieval assembly according to any of the precedingclauses, wherein each of the plurality of shape memory elongate clotcapturing elements has a proximal end and a distal end that arerespectively welded to the proximal and distal collars.

Clause 13. The clot retrieval assembly according to any of the precedingclauses, wherein the plurality of shape memory elongate clot capturingelements and the proximal and distal collars are formed from a singlepiece of material.

Clause 14. The clot retrieval assembly according to any of the precedingclauses, wherein the distal collar has an atraumatic distal tip.

Clause 15. The clot retrieval assembly according to any of the precedingclauses, further comprising:

-   -   a second retrieval device located on the elongate wire distal to        the first retrieval device, the second retrieval device        comprising:        -   a distal collar fixed stationary on the elongate wire;        -   a proximal collar being slideable along a portion of the            length of the elongate wire; and        -   a plurality of shape memory elongate clot capturing elements            that each has a proximal end coupled to the proximal collar            of the second retrieval device and a distal end coupled to            the distal collar of the second retrieval device, each of            the plurality of shape memory elongate capturing elements            having a proximal end portion and a distal end portion;        -   the second retrieval device being configured to transition            from a radially constrained state to an expanded rest state,            in the radially constrained state the proximal collar of the            second retrieval device is located at a first axial position            on the elongate wire proximal to the distal collar of the            second retrieval device and is spaced apart from the distal            collar of the second retrieval device by a first distance,            in the expanded rest state the proximal collar of the second            retrieval device is located at a second axial position on            the elongate wire proximal to the distal collar of the            second retrieval device and is spaced apart from the distal            collar of the second retrieval device by a second distance            that is less than the first distance.

Clause 16. The clot retrieval assembly according to clause 15, whereinwhen the second retrieval device is in the radially constrained state noportion of the plurality of shape memory elongate clot capturingelements is located proximal to the proximal collar and when the secondretrieval device is in the radially expanded state at least some of theproximal portions of the plurality of shape memory elongate clotcapturing elements are inverted around the proximal collar with at leastsome of the proximal portions of the plurality of shape memory elongateclot capturing elements being disposed proximal to the proximal collar.

Clause 17. The clot retrieval assembly according to clauses 15 and 16,wherein when the second retrieval device is in the expanded rest statethe proximal collar is movable distally to a third axial position on theelongate wire proximal to the distal collar and is spaced apart from thedistal collar by a third distance that is less than the second distance.

Clause 18. The clot retrieval assembly according to clause 1, furthercomprising:

-   -   a second retrieval device located on the elongate wire proximal        to the first retrieval device, the second retrieval device        comprising:        -   a proximal collar fixed stationary on the elongate wire;        -   a distal collar being slideable along a portion of the            length of the elongate wire; and        -   a plurality of shape memory elongate clot capturing elements            that each has a proximal end coupled to the proximal collar            of the second retrieval device and a distal end coupled to            the distal collar of the second retrieval device, each of            the plurality of shape memory elongate capturing elements            having a proximal end portion and a distal end portion;        -   the second retrieval device being configured to transition            from a radially constrained state to an expanded rest state,            in the radially constrained state the distal collar of the            second retrieval device is located at a first axial position            on the elongate wire proximal to the proximal collar of the            second retrieval device and is spaced apart from the            proximal collar of the second retrieval device by a first            distance, in the expanded rest state the distal collar of            the second retrieval device is located at a second axial            position on the elongate wire distal to the proximal collar            of the second retrieval device and is spaced apart from the            proximal collar of the second retrieval device by a second            distance that is less than the first distance.

Clause 19. The clot retrieval assembly according to clause 18, whereinwhen the second retrieval device is in the radially constrained state noportion of the plurality of shape memory elongate clot capturingelements is located distal to the distal collar and when the secondretrieval device is in eh expanded rest state at least some of thedistal portions of the plurality of shape memory elongate clot capturingelements are inverted around the distal collar with at least some of thedistal portions of the plurality of shape memory elongate clot capturingelements being disposed distal to the distal collar.

Group B Clauses:

Clause 1. A clot retrieval assembly comprising:

-   -   an elongate wire having a length and a longitudinal axis;    -   a first retrieval device comprising:        -   a distal collar fixed stationary on the elongate wire;        -   a proximal collar being slideable along a portion of the            length of the elongate wire; and        -   a plurality of shape memory elongate clot capturing elements            that each has a proximal end coupled to the proximal collar            and a distal end coupled to the distal collar;        -   the first retrieval device being configured to transition            from a radially constrained state to an expanded rest state            and from the expanded rest state to an expanded stressed            state, in the radially constrained state the proximal collar            is located at a first axial position on the elongate wire            proximal to the distal collar and is spaced apart from the            distal collar by a first distance, in the expanded rest            state the proximal collar is located at a second axial            position on the elongate wire proximal to the distal collar            and is spaced apart from the distal collar by a second            distance that is less than the first distance, in the            expanded stressed state the proximal collar is located at a            third axial position on the elongate wire proximal to the            distal collar and is spaced apart from the distal collar by            a third distance that is less than the second distance.

Clause 2. The clot retrieval assembly according to clause 1, whereinwhen the first retrieval device is in the radially constrained state noportion of each of the plurality of shape memory elongate clot capturingelements bends back on itself.

Clause 3. The clot retrieval assembly according to clause 1, whereinwhen the first retrieval device is in the radially constrained state noportion of the plurality of shape memory elongate clot capturingelements is located proximal to the proximal collar.

Clause 4. The clot retrieval assembly according to any of the precedingclauses, wherein the second length is 30% to 60% the first length.

Clause 5. The clot retrieval assembly according to any of the precedingclauses, wherein when the first retrieval device is in the expanded reststate at least portions of some of the plurality of shape memoryelongate clot capturing elements extend proximal to the proximal collar.

Clause 6. The clot retrieval assembly according to any of the precedingclauses, wherein when the first retrieval device is in the expanded reststate at least some of the plurality of shape memory elongate clotcapturing elements take a path from the proximal collar to the distalcollar with a first portion of the path extending in a proximaldirection and a second portion of the path extending in a distaldirection.

Clause 7. The clot retrieval assembly according to clause 1, whereinwhen the first retrieval device in the expanded rest state the firstretrieval device includes a proximal inverted portion and a distalnon-inverted portion, the proximal inverted portion being composed ofproximal end portions of the shape memory elongate clot capturingelements, the distal non-inverted portion being composed of distal endportions of the shape memory elongate clot capturing elements.

Clause 8. The clot retrieval assembly according to clause 7, wherein theproximal inverted portion does not exists when the first retrievaldevice is in the radially constrained state.

Clause 9. The clot retrieval assembly according to any of the precedingclauses, wherein when the proximal collar is in the second axialposition one or more of the shape memory elongate clot capturingelements has a first stiffness, and when the proximal collar is in thethird axial position the one or more shape memory elongate clotcapturing elements has a second stiffness greater than the firststiffness.

Clause 10. The clot retrieval assembly according to clause 7, whereinthe distal non-inverted portion of the first retrieval device includes apermeable cover.

Clause 11. The clot retrieval assembly according to any of the precedingclauses, wherein each of the plurality of shape memory elongate clotcapturing elements has a proximal end and a distal end that arerespectively attached to the proximal and distal collars by an adhesive.

Clause 12. The clot retrieval assembly according to any of the precedingclauses, wherein each of the plurality of shape memory elongate clotcapturing elements has a proximal end and a distal end that arerespectively attached to the proximal and distal collars by a solder.

Clause 13. The clot retrieval assembly according to any of the precedingclauses, wherein each of the plurality of shape memory elongate clotcapturing elements has a proximal end and a distal end that arerespectively welded to the proximal and distal collars.

Clause 14. The clot retrieval assembly according to any of the precedingclauses, wherein plurality of the shape memory elongate clot capturingelements and the proximal and distal collars are formed from a singlepiece of material.

Clause 15. The clot retrieval assembly according to any of the precedingclauses, wherein the distal collar has an atraumatic distal tip.

Clause 16. The clot retrieval assembly according to clause 1, furthercomprising:

-   -   a second retrieval device located on the elongate wire distal to        the first retrieval device,    -   the second retrieval device comprising:        -   a distal collar fixed stationary on the elongate wire;        -   a proximal collar being slideable along a portion of the            length of the elongate wire; and        -   a plurality of shape memory elongate clot capturing elements            that each has a proximal end coupled to the proximal collar            of the second retrieval device and a distal end coupled to            the distal collar of the second retrieval device;        -   the second retrieval device being configured to transition            from a radially constrained state to an expanded rest state,            in the radially constrained state the proximal collar of the            second retrieval device is located at a first axial position            on the elongate wire proximal to the distal collar of the            second retrieval device and is spaced apart from the distal            collar of the second retrieval device by a first distance,            in the expanded rest state the proximal collar of the second            retrieval device is located at a second axial position on            the elongate wire proximal to the distal collar of the            second retrieval device and is spaced apart from the distal            collar of the second retrieval device by a second distance            that is less than the first distance.

Clause 17. The clot retrieval assembly according to clause 16, whereinwhen the second retrieval device is in the expanded rest state theproximal collar is movable distally to a third axial position on theelongate wire proximal to the distal collar and is spaced apart from thedistal collar by a third distance that is less than the second distance.

Clause 18. The clot retrieval assembly according to clause 1, furthercomprising:

-   -   a second retrieval device located on the elongate wire proximal        to the first retrieval device, the second retrieval device        comprising:        -   a proximal collar fixed stationary on the elongate wire;        -   a distal collar being slideable along a portion of the            length of the elongate wire; and        -   a plurality of shape memory elongate clot capturing elements            that each has a proximal end coupled to the proximal collar            of the second retrieval device and a distal end coupled to            the distal collar of the second retrieval device;        -   the second retrieval device being configured to transition            from a radially constrained state to an expanded rest state,            in the radially constrained state the distal collar of the            second retrieval device is located at a first axial position            on the elongate wire proximal to the proximal collar of the            second retrieval device and is spaced apart from the            proximal collar of the second retrieval device by a first            distance, in the expanded rest state the distal collar of            the second retrieval device is located at a second axial            position on the elongate wire distal to the proximal collar            of the second retrieval device and is spaced apart from the            proximal collar of the second retrieval device by a second            distance that is less than the first distance.

Group C Clauses:

Clause 1. A method of making a clot retrieval assembly, the methodcomprising:

-   -   obtaining a first collar having a proximal end, a distal end, a        central longitudinal through opening extending between and        through the proximal and distal ends, and a plurality of        longitudinal channels located in the proximal end around the        central longitudinal through opening, the central longitudinal        through opening having a central axis;    -   obtaining a second collar having a proximal end, a distal end, a        central through opening extending between and through the        proximal and distal ends of the second collar, and a plurality        of channels located in the distal end of the second collar        around the central through opening of the second collar, the        central longitudinal through opening of the second collar having        a central axis;    -   obtaining a plurality of elongate elements that each has a        proximal end, a distal end and a length;    -   fixing the first end of each of the plurality of elongate        elements inside a respective one of the plurality of channels in        the first collar;    -   fixing the second end of each of the plurality of elongate        elements inside a respective one of the plurality of channels in        the second collar;    -   axially aligning the central axes of the central through        openings of the first and second collars;    -   after axially aligning the central axes of the central through        openings of the first and second collars, applying an axial        force to one or both of the first and second collars to cause        one or both of the first and second collars to move axially        towards the other so that the plurality of elongate elements        invert around the second collar;    -   shape-setting the plurality of elongate elements while the        plurality of elongate elements are inverted around the second        collar; and    -   mounting the proximal and distal collars on a distal end portion        of an elongate wire with the distal collar being fixed        stationary on the elongate wire and the proximal collar being        slideable on the elongate wire.

Clause 2. The method according to clause 1, further comprising rotatingone or both of the first and second collars with respect to the otherwhile the plurality of elongate elements invert around the secondcollar.

Clause 3. The method according to clause 1, further comprising rotatingone or both of the first and second collars with respect to the otherafter the plurality of elongate elements invert around the secondcollar.

Clause 4. The method according to any of the preceding clauses, whereinone or both of the first and second collars is made of a radiopaquematerial.

Clause 5. The method according to any of the preceding clauses, whereinone or both of the first and second collars is coated with a radiopaquematerial.

Clause 6. The method according to any of the preceding clauses, whereinthe plurality of elongate elements are made of Nitinol.

Clause 7. The method according to any of the preceding clauses, furthercomprising attaching to one or more of the plurality of elongateelements a permeable cover that extends circumferentially around aportion of the plurality of elongate elements.

Clause 8. The method according to any of the preceding clauses, furthercomprising shaping the plurality of elongate elements by use of afixture prior to shape-setting the plurality of elongate elements.

Clause 9. The method according to any of the preceding clauses, whereinthe plurality of the elongate elements comprise wires.

Clause 10. The method according to any of the preceding clauses, whereinthe plurality of the elongate elements comprise ribbons.

Clause 11. The method according to clause 9, wherein some of the wireshave a first diameter and some of the wires have a second diameter lessthan the first diameter.

Clause 12. The method according to clause 10, wherein some of theplurality of ribbons have a first width and some of the plurality ofelongate elements have a second width less than the first width.

Clause 13. The method according to any of the preceding clauses, whereinthe first collar has an atraumatic tip.

Clause 14. The method according to any of the preceding clauses whereinthe first collar has an atraumatic tip and the second collar has anatraumatic tip.

Clause 15. The method according to any of the preceding clauses, furthercomprising radially constraining the retrieval device inside a sheath.

Clause 16. The method according to clause 15, wherein the retrievaldevice is radially constrained inside the sheath such that no portionsof the shape memory elongate clot capturing elements reside proximal tothe proximal collar.

Group D Clauses:

Clause 1. A method of making a clot retrieval device, the methodcomprising:

-   -   obtaining a cylindrical tube having a proximal end, a distal        end, a length and a central longitudinal axis, the tube having a        plurality of circumferentially spaced-apart continuous elongate        slots that each extends along a portion of the length of the        tube, residing between each adjacent set of spaced-apart        elongate slots is an elongate clot capturing element, each of        the elongate slots having a proximal end and a distal end that        are respectively spaced-apart from the proximal and distal ends        of the tube, the tube including a proximal collar disposed        between the proximal ends of the elongate slots and the proximal        end of the tube, the tube including a distal collar disposed        between the distal ends of the elongate slots and the distal end        of the tube, each of the elongate clot capturing elements having        a proximal end portion and a distal end portion;    -   applying a distally directed force to the proximal collar and/or        the distal collar to cause at least some of the proximal        portions of the elongate clot capturing elements to invert        around the proximal collar;    -   shape-setting the plurality of elongate elements while the        plurality of elongate elements are inverted around the proximal        collar.

Clause 2. The method according to clause 1, further comprising rotatingone or both of the proximal and distal collars with respect to the otherwhile the plurality of elongate elements invert around the secondcollar.

Clause 3. The method according to clause 1, further comprising rotatingone or both of the proximal and distal collars with respect to the otherafter the plurality of elongate elements invert around the secondcollar.

Clause 4. The method according to any of the preceding clauses, whereinone or both of the proximal and distal collars is coated with aradiopaque material.

Clause 5. The method according to any of the preceding clauses, whereinthe tube is made of Nitinol.

Clause 6. The method according to any of the preceding clauses, furthercomprising attaching to one or more of the clot capturing elements apermeable cover that extends circumferentially around the distal endportions of elongate clot capturing elements.

Clause 7. The method according to any of the preceding clauses, furthercomprising shaping the plurality of elongate clot capturing elements byuse of a fixture prior to shape-setting the elongate clot capturingelements.

Clause 8. The method according to any of the preceding clauses, whereineach of the elongate clot capturing elements includes an area of reducedthickness.

Clause 9. The method according to clause 8, wherein the areas of reducedthickness are configured to cause an initial buckling of the elongateclot capturing elements in the areas of reduced thickness when thedistally directed force is applied to the proximal collar and/or theproximally directed force is applied to the distal collar.

Clause 10. The method according to any of the preceding clauses, whereinthe proximal end portions of the elongate clot capturing elements have afirst width and the distal end portions of the elongate clot capturingelements have a second width different than the first width.

Clause 11. The method according to clause 10, wherein the second widthis greater than the first width.

Clause 12. The method according to any of the preceding clauses, whereinprior to the distally directed force be applied to the proximal collarand/or the proximally directed force being applied to the distal collar,the proximal end portions of the elongate clot capturing elements curveabout the longitudinal axis of the tube.

Clause 13. The method according to any of the preceding clauses, whereinthe proximal end portions of the elongate clot capturing elements arearranged helical with respect to the longitudinal axis of the tube.

Clause 14. The method according to any of the preceding clauses, whereinthe distal end portions of the elongate clot capturing elements arestraight.

Clause 15. The method according to clause 14, wherein the straightdistal end portions of the elongate clot capturing elements are arrangedparallel to the longitudinal axis of the tube.

Clause 16. The method according to clause 12, wherein the distal endportions of the elongate clot capturing elements are curved.

Clause 17. The method according to clause 12, wherein the proximal endportions of the elongate capturing elements have a first length and thedistal end portions of the elongate capturing elements have a secondlength shorter than the first length.

Clause 18. The method according to clause 1, wherein each of theelongate clot capturing elements includes an area of reduced width.

Clause 19. The method according to clause 18, wherein the areas ofreduced width are configured to cause an initial buckling of theelongate clot capturing elements in the areas of reduced width when thedistally directed force is applied to the proximal collar and/or theproximally directed force is applied to the distal collar.

Clause 20. The method according to clause 1, wherein the elongate clotcapturing elements include an intermediate portion located between theproximal and distal end portions, the proximal and distal end portionsof the elongate capturing elements being arranged circumferentiallyoffset from one another and being joined by the intermediate portion.

Clause 21. The method according to clause 1, wherein prior to thedistally directed force be applied to the proximal collar and/or theproximally directed force being applied to the distal collar, each ofthe circumferentially spaced-apart continuous elongate slots has alength that is greater than or equal to 70% the length of thecylindrical tube.

Group E Clauses:

Clause 1. A method of making a clot retrieval device, the methodcomprising:

-   -   obtaining a cylindrical tube having a proximal end, a distal        end, a length and a central longitudinal axis, the tube having a        plurality of circumferentially spaced-apart continuous elongate        slots that each extends along a portion of the length of the        tube, residing between each adjacent set of spaced-apart        elongate slots is an elongate clot capturing element, each of        the elongate slots having a proximal end and a distal end that        are respectively spaced-apart from the proximal and distal ends        of the tube, the tube including a proximal collar disposed        between the proximal ends of the elongate slots and the proximal        end of the tube, the tube including a distal collar disposed        between the distal ends of the elongate slots and the distal end        of the tube, each of the elongate clot capturing elements having        a proximal end portion and a distal end portion;    -   applying a distally directed force to the proximal collar and/or        the distal collar to cause at least some of the proximal        portions of the elongate clot capturing elements to invert        around the proximal collar;    -   shape-setting the plurality of elongate elements while the        plurality of elongate elements are inverted around the proximal        collar; and    -   mounting the proximal and distal collars on a distal end portion        of an elongate wire with the distal collar being fixed        stationary on the elongate wire and the proximal collar being        slideable on the elongate wire.

Clause 2. The method according to clause 1, further comprising rotatingone or both of the proximal and distal collars with respect to the otherwhile the plurality of elongate clot capturing elements invert aroundthe second collar.

Clause 3. The method according to clause 1, further comprising rotatingone or both of the proximal and distal collars with respect to the otherafter the plurality of elongate clot capturing elements invert aroundthe second collar and prior to shape-setting the plurality of elongateclot capturing elements.

Clause 4. The method according to any of the preceding clauses, whereinone or both of the proximal and distal collars is coated with aradiopaque material.

Clause 5. The method according to any of the preceding clauses, whereinthe tube is made of Nitinol.

Clause 6. The method according to any of the preceding clauses, furthercomprising attaching to one or more of the elongate clot capturingelements a permeable cover that extends circumferentially around thedistal end portions of elongate clot capturing elements.

Clause 7. The method according to any of the preceding clauses, furthercomprising shaping the plurality of elongate clot capturing elements byuse of a fixture prior to shape-setting the elongate clot capturingelements.

Clause 8. The method according to any of the preceding clauses, whereineach of the elongate clot capturing elements includes an area of reducedthickness.

Clause 9. The method according to clause 8, wherein the areas of reducedthickness are configured to cause an initial buckling of the elongateclot capturing elements in the areas of reduced thickness when thedistally directed force is applied to the proximal collar and/or theproximally directed force is applied to the distal collar.

Clause 10. The method according to clause 1, wherein the proximal endportions of the elongate clot capturing elements have a first width andthe distal end portions of the elongate clot capturing elements have asecond width different first width.

Clause 11. The method according to clause 10, wherein the second widthis greater than the first width.

Clause 12. The method according to any of the preceding clauses, whereinprior to the distally directed force be applied to the proximal collarand/or the proximally directed force being applied to the distal collar,the proximal end portions of the elongate clot capturing elements curveabout the longitudinal axis of the tube.

Clause 13. The method according to any of the preceding clauses, whereinthe proximal end portions of the elongate clot capturing elements arearranged helical with respect to the longitudinal axis of the tube.

Clause 14. The method according to clause 12, wherein the distal endportions of the elongate clot capturing elements are straight.

Clause 15. The method according to clause 14, wherein the straightdistal end portions of the elongate clot capturing elements are arrangedparallel to the longitudinal axis of the tube.

Clause 16. The method according to clause 12, wherein the distal endportions of the elongate clot capturing elements are curved.

Clause 17. The method according to clause 12, wherein the proximal endportions of the elongate capturing elements have a first length and thedistal end portions of the elongate capturing elements have a secondlength shorter than the first length.

Clause 18. The method according to any of the preceding clauses, whereineach of the elongate clot capturing elements includes an area of reducedwidth.

Clause 19. The method according to clause 18, wherein the areas ofreduced width are configured to cause an initial buckling of theelongate clot capturing elements in the areas of reduced width when thedistally directed force is applied to the proximal collar and/or theproximally directed force is applied to the distal collar.

Clause 20. The method according to clause 1, wherein the elongate clotcapturing elements include an intermediate portion located between theproximal and distal end portions, the proximal and distal end portionsof the elongate capturing elements being arranged circumferentiallyoffset from one another and being joined by the intermediate portion.

Clause 21. The method according to clause 1, wherein prior to thedistally directed force be applied to the proximal collar and/or theproximally directed force being applied to the distal collar, each ofthe circumferentially spaced-apart continuous elongate slots has alength that is greater than or equal to 70% the length of thecylindrical tube.

What is claimed is:
 1. A method of making a clot retrieval device (20),the method comprising: obtaining a cylindrical tube made of shape memorymaterial, the cylindrical tube having a proximal end, a distal end, alength and a central longitudinal axis, the tube being cut to have aplurality of circumferential spaced-apart continuous elongate slots thateach extends along a portion of the length of the tube so that residingbetween each adjacent set of spaced-apart elongate slots is an elongateclot capturing element, each of the elongate slots having a proximal endand a distal end that are respectively spaced-apart from the proximaland distal ends of the tube, the tube including a proximal collardisposed between the proximal ends of the elongate slots and theproximal end of the tube, the tube including a distal collar disposedbetween the distal ends of the elongate slots and the distal end of thetube, each of the elongate clot capturing elements having a proximal endportion and a distal end portion; applying a distally directed force tothe proximal collar and/or a proximally directed force to the distalcollar to cause at least some of the proximal portions of the elongateclot capturing elements to invert around the proximal collar so that atleast some of the proximal end portions of the elongate clot capturingelements are disposed proximal to a distal end of the proximal collar;shape-setting the plurality of elongate colt capturing elements whilethe plurality of elongate clot capturing elements are inverted aroundthe proximal collar; and mounting the proximal and distal collars on adistal end portion of an elongate wire with the distal collar beingfixed stationary on the elongate wire and the proximal collar beingslideable on the elongate wire.
 2. The method according to claim 1,further comprising rotating one or both of the proximal and distalcollars with respect to the other while the plurality of elongate clotcapturing elements invert around the proximal collar.
 3. The methodaccording to claim 1, further comprising rotating one or both of theproximal and distal collars with respect to the other after theplurality of elongate clot capturing elements invert around the secondproximal collar and prior to shape-setting the plurality of elongateclot capturing elements.
 4. The method according to claim 1, wherein oneor both of the proximal and distal collars is coated with a radiopaquematerial.
 5. The method according to claim 1, wherein the tube is madeof Nitinol.
 6. The method according to claim 1, further comprisingattaching to one or more of the elongate clot capturing elements apermeable cover that extends circumferentially around the distal endportions of elongate clot capturing elements.
 7. The method according toclaim 1, further comprising shaping the plurality of elongate clotcapturing elements by use of a fixture prior to shape-setting theelongate clot capturing elements.
 8. The method according to claim 1,wherein each of the elongate clot capturing elements is formed to havean area of reduced thickness.
 9. The method according to claim 8,wherein the areas of reduced thickness are configured to cause aninitial bending of the elongate clot capturing elements in the areas ofreduced thickness when the distally directed force is applied to theproximal collar and/or the proximally directed force is applied to thedistal collar.
 10. The method according to claim 1, wherein the proximalend portions of the elongate clot capturing elements are formed to havea first width and the distal end portions of the elongate clot capturingelements are formed to have a second width different than the firstwidth.
 11. The method according to claim 10, wherein the second width isgreater than the first width.
 12. The method according to claim 1,wherein prior to the distally directed force being applied to theproximal collar and/or the proximally directed force being applied tothe distal collar, the proximal end portions of the elongate clotcapturing elements curve about the longitudinal axis of the tube. 13.The method according to claim 12, wherein the distal end portions of theelongate clot capturing elements are straight.
 14. The method accordingto claim 13, wherein the straight distal end portions of the elongateclot capturing elements are arranged parallel to the longitudinal axisof the tube.
 15. The method according to claim 12, wherein the distalend portions of the elongate clot capturing elements are curved.
 16. Themethod according to claim 12, wherein the proximal end portions of theelongate capturing elements have a first length and the distal endportions of the elongate capturing elements have a second length shorterthan the first length.
 17. The method according to claim 1, wherein theproximal end portions of the elongate clot capturing elements extendhelically about the longitudinal axis of the tube.
 18. The methodaccording to claim 1, wherein each of the elongate clot capturingelements includes an area of reduced width.
 19. The method according toclaim 18, wherein the areas of reduced width are configured to cause aninitial bending of the elongate clot capturing elements in the areas ofreduced width when the distally directed force is applied to theproximal collar and/or the proximally directed force is applied to thedistal collar.
 20. The method according to claim 1, wherein the elongateclot capturing elements include an intermediate portion located betweenthe proximal and distal end portions, the proximal and distal endportions of the elongate capturing elements being arrangedcircumferentially offset from one another and being joined by theintermediate portion.
 21. The method according to claim 1, wherein priorto the distally directed force be applied to the proximal collar and/orthe proximally directed force being applied to the distal collar, eachof the circumferentially spaced-apart continuous elongate slots has alength that is greater than or equal to 70% the length of thecylindrical tube.